Added a colour ID TreeView::selectedItemBackgroundColourId, and changed the TreeView to fill selected items with this. (The colour is set to transparent by default so this won't affect existing code).
Updated the LookAndFeel::drawTreeviewPlusMinusBox and TreeViewItem::paintOpenCloseButton methods to provide more flexibility.
Renamed and refactored the LookAndFeel classes. The LookAndFeel class is now an abstract base-class, and there are 3 concrete subclasses you can use. These are LookAndFeel_V1 (replaces OldSchoolLookAndFeel), LookAndFeel_V2 (replaces what was the normal LookAndFeel class) and LookAndFeel_V3 (this is a new style, taken from the Introjucer's L+F).
Version number update