Fixed: highlighted table cells with CPTableViewSelectionHighlightStyleNone had white text.

Previously, CPTableView was unconditionally setting the selected theme state for selected data views. When the selection highlight style is CPTableViewSelectionHighlightStyleNone, there is no row selection highlighting done. Since the default theme specifies white text for selected data views, we ended up with white text on a non-highlighted background, which was invisible on non-alternate rows and almost invisible on alternate rows.

This commit unsets the selected theme state flag for any redrawn data views when the selection highlight style is CPTableViewSelectionHighlightStyleNone, thus the text color does change at all when selected.

Fixes #1847