Merged in masterschlumpf/beremiz/generate-button (pull request #38)

"Generate Prgram" button

Approved-by: Andrey Skvortsov <andrej.skvortzov@gmail.com>

Create a "Generate Program As..." menu to make the "Generate Program" toolbutton even more useful.

The behaviour is the same as "Save" and "Save As...". Now "Generate Program" uses the last filename
if known and "Generate Progam As..." asks every time.

Add "Generate Program" to toolbar in PLCOpenEditor standalone mode.

Currently you can find the "Generate Program" action only in the file menu,
but this action is very often used in standalone mode, so I added toolbuffon.