Python interpreter updates.

Code cleanup.
Added Python version banner to pythonQt widget.
Added history support to pythonQt widget.

Signed-off-by: Tomasz CEDRO <CeDeROM@tlen.pl>
QtMainWindow updates and cleanups.

Style initialization was moved to allow '-style' commandline
parameter to set desired QtStyle.

Signed-off-by: Tomasz CEDRO <CeDeROM@tlen.pl>