* d2ui/UIFrame: Refactor into its own class
it's not useful to have the handling of frames for the
inventory/herostate/skilltree/quest panels individually in each of
those.
* d2ui/button: Fix crash when a buttonlayout was not allowing FrameChange
When AllowFrameChange is false we do not create pressedSurface. So if we
press the button the game will crash.
* d2ui/button: Allow label-only buttons
At least for the skillmenu we need buttons were the graphic size does
not match the buttonsize. So let's render the graphic in there and make
the button label only.
* d2hero/hero_state_factory: Give all heroes their class specific skills
* d2player/gamecontrols: Fix wrong inventory/stats layouts for exp chars
For Druid/Assassin the inventory frame was rendered for a 640x480
resolution. This brings it in line with all other characters.
* d2player: Add inital Skilltree panel
* d2player/game_controls: Enable skilltree
Note here, that the inventory panel and skilltree panel can overlap.
* d2player/skilltree: Add skillicon rendering
Note here, that I couldn't figure out how to render them dark if no
skillpoints are invested.
Signed-off-by: juander <juander@rumtueddeln.de>
