Move combo render function calls to wz.
Move window render function calls to wz.
Move tab page render function calls to wz.
Cleanup/remove wzcpp tab code.
Handle creating and destroying dock tabs internally.
Create tabbed widget tab bar internally.
Create dock tab bars internally.
Changed wz_tab_bar_add_tab to wz_tab_bar_create_tab. Return a tab/button instead of passing one in.
Don't need to call wz_widget_resize_to_measured when dock tab button is added.
Use tab button drawing.
Handle dock icon and preview drawing internally.