allow set tab width for textviews
minor refactorings
gui base test case
refactored documentation lexing/parsing

allow integers in the form 002 as they are recognized by python
more strict parsing
correct python code tokenization
automatic numbering handled by parser
minor reformattings
moved .ui files to resources subdirectory
utils.get_luminance accepts color objects/strings
strip whitespace when displaying documentation in strfmt_dialog
added GtkSourceView support to edit_dialog
updated readme