* Workaround the Windows pangocairo bug by drawing text
with curves. Remove some of the meters.
* Remove terminal lines from meters and voltage sources,
add vertical terminal points instead.
* Add bipolar, IGFET and JFET transistors.
* Add more variants to some symbols.
* Add a symbol for a simple terminal.
* Avoid unneccessary stroke() calls.
* Fix comments.
The lucky ones are: capacitor, resistor and diode.
More symbols can be expected later, when more cairo
functions are exported to Lua and relevant standards
become accessible to me.