Provides pixmaps for all Qt standard icons, as an extension, with
descriptions on how to use QCommonStyle to override the default standard
icons. This provides a consistent look and feel on all apps.
Added an example PyQt6 application with a workaround to attempt to fix
the placeholder text color issues, which further supports the idea that
it is a Qt bug, and not a stylesheet issue.
Using `QtGui.QPalette.ColorRole.PlaceholderText`, we are able to modify
the placeholder text color in Qt5, but not in Qt6.
Closes#41.
Closes#44.
Added `example/standard_icons.py` which subclasses `QCommonStyle` to
override standard icons, while keeping the default style. This respects
the stylesheet, while allowing custom standard icons. Added this example
to the documentation.
Closes#33.
Alex Huszagh