CHANGES:
Version 6.7: Fixed source(,S) and ttmotor to work correctly with labels.
  Simplified several 2-terminal macros by using the reversed macro.
Version 6.6: New macros memristor, centerline.  Revised PSTricks patch.
  Options in mosfet, capacitor.  Opamp .C defined. Tweaks to avoid
  potential name conflicts. Fix for dashline.
Version 6.5: New macros Loopover_, m4xpand, showbox_, gyrator, norator,
  nullator, nterm, rotellipse, rotbox. Logic gate examples.
  Customization arguments for non-2-terminal elements.  Signal
  flow-graph macros tuned to allow large nodes; bugfix in sfgarc.  A
  patch for PSTricks to work around the context dependency of \psbezier
  within \pscustom.
Version 6.4: New macros Equidist3, f_box, rs_box, Darlington, View3D.
  Options for diode, inductor, transformer, consource.  Moved arrowhead
  initialization in pstricks.m4 and libcct.m4 for for more flexibility
  with diagrams embedded in latex files.
Version 6.3: New options for mosfet, diode, earphone. Better color support.
  Fixed system-dependent OR_gate problems. New macro cintersect.
Version 6.2: Replaced scr with a variant of thyristor. Bug-fix in
  bi_trans. Options for source.
Version 6.1: New macros ttmotor, thyristor. Options for source, bi_trans,
  transformer.  More robust arcd, arcr.
Version 6.0: TikZ PGF compatibility.  Added transformer labels, optional
  FlipFlop labels. New macros dswitch, winding.  Tweaked nport, source,
  bi_trans, AND_gen, OR_gen, sinusoid, resistor.
Version 5.9: Simplified internal flags for pic processor and postprocessor.
  New antenna, cbreaker, dturn, and lbox macros.  Several changes to
  allow sprintf string arguments.  New options for buzzer, capacitor,
  dimension_, ebox, fuse, mosfet, source, and switch.  Fix of drjust.
  Better compatibility with pic macros.  Numerous changes to documentation.
Version 5.8:
  Simplified installation.  Revised and augmented logic-gate library.
  Cleaner libgen macro output.  Improved b_current, bi_trans, ground,
  dtee.  Dline and darrow corrected for gpic. New macros dashline, m4xtract.
Version 5.7: Psfrag examples.  Improved dline.  Added option and label in
  igbt.  Bug fix in tr_xy.  Multiple-emitter option in bi_trans.
Version 5.6: Better MetaPost, PDFLaTeX, and xfig support.  PDF examples.
  Reworked diode for easier customization and more options.  Improved
  shade, sfgline, dline, darrow, gap, point_, Point_, opamp, bi_trans,
  variable, em_arrows, larrow, rarrow, FlipFlop6.  New speaker, bell,
  microphone, buzzer.  Negated logic gate inputs and IEEE box logic gates.
Version 5.5: New macros potentiometer, variable, igbt, tline. Optional
  negated logic gate inputs. Options for diode, source.
Version 5.4: New Mux, for_, arca.  Reworked gate macros FlipFlop, AND_gate,
  OR_gate, NOT_gate.  Improved lg_pintxt, boxdim, s_box, s_ht, s_wd,
  s_dp, nport, resistor, opamp.  Completely reworked bi_tr, mosfet;
  deleted smosfet.  Minor additions and changes to the manual.
Version 5.3: New macros arcr, arcd, beginshade, endshade, larrow, rarrow,
  s_sp, s_ht, s_wd, Max, Min, sfgself.  Improved ground, sfgnode, diode,
  resistor.
Version 5.2: New macros arrowline, nport, vlength, boxcoord, reversed.
  Improved s_box, sfg_init, cross, fitcurve, sinusoid, transformer, darrow,
  mosfet, psset_, battery, diode, capacitor.
Version 5.1: Signal-flow graph (directed graph) macros.  More consistent
  rot3Dz.  Work-around for a bug in some pic processors invoked by the
  battery macro and for an arc instability invoked by the fuse macro.
  Modified ground, dimension_, par_, label macros, b_current, diode,
  transformer.  New macros gpar_, ujt, scr, contact, relay.
  Document fixes and additions.  Changes to examples for portability.
Version 5.0: Macros fuse, lpop, sinc; dpic-only sinusoid and fitcurve macros.
  More robust mosfet, smosfet, b_current, bi_tr, j_fet, intersect_.
  Editorial changes to the manual. Examples in Xfig version 3.2 format.
  Web-based examples and updated links.
Version 4.9: More robust NOT_gate.  Function pmod(), macro shade().  Tweaks
  to diode, dend, crossover. Newer manual and web references.  Binary
  tree and flowchart macros.
Version 4.8: More robust ebox, source, shadebox, gap.  Modified d_fet and
  e_fet.  Macros mosfet and smosfet.  More examples in the manual.  Bug
  fixes in Fector, transformer, BUFFER_gate and in sum_, abs_, neg_, sign_ (!).
Version 4.7: Fixed the excess-space bug in boxdims.sty.  Added Macros s_box,
  s_init, scale changes to make the package more metric-friendly.  Reworked
  amp, integrator, opamp, diode, battery and a few other macros for robustness
  and clarity.  Minor document changes.
Version 4.6: Percent-signs at the end of pstricks-generated lines.
  Index in the manual.  New copyright notices.
Version 4.5: Options for several 2-terminal macros.  Minor bug fixes and
  better robustness.  Documents edited for friendlier PC installation and use.
Version 4.3: Macros pt__ and boxdim.  Additions to the manual.  More robust
  dimension_, tuned FlipFlop for xfig.  PC installation information.
Version 4.2: Friendlier manual.  New Xfig prototype file to allow correct
  scaling.  Cleaned up b_current, added line_leng.  Changes and additions
  to logic gates.
Version 4.1: Xfig prototype file included.  Minor document changes.  Fixed
  recursive call bug and blank line bug.  Changed argument for dend
  macro.  Better arrowheads in circuit elements.
Version 4: Simplified library use.  Added capabilities and flexibility to
  several devices, added _init macros, modified b_current.  Updated
  font.m4, cosmetic changes to inductor.  Made gamp, amp, opamp,
  integrator more robust.  Deleted edel_ macro.  Fixed elen_ bug in
  darrow.m4.  Removed Capacitor, Inductor and others in favour of
  parameterized macros.  Iron-core inductors.  Re-worked use of arcs in
  basic elements for better robustness.  Edited examples document and
  the manual.
Version 3: Document changes, minor changes to dimension_, switch,
  ground, battery.  Added flexibility for several elements.  New
  diodes, Capacitor, transistors, hop, transformer.  Experimental
  Metafont version of basic elements.
Version 2.2: Replaced definitions of two-terminal elements
  with current arrow by an arrow-labelling macro.
Version 2.1: one or two examples simplified, and logic gates added.
Version 2:  considerable added flexibility and robustness,
  bug fixes, a few new constructs, a manual, and a complex logic-gate
  example.