CGE2: Fix compilation broken by previous commit.
CGE2: Rework Sprite::touch to use V2D for coords.
CGE2: Rework show() and hide() in Bitmap to use V2Ds as parameters.
CGE: Remove (broken) variable length specification
CGE2: Implement switching between scenes.

Minor modification in Spare again to do so.
CGE2: Fix initialization of _posTab.

Fixes a possible memory leak.
CGE2: Fix coords of misplaced speech bubbles.

The origin of the bug is that when we added the command (triggered by a mouse-click on a sprite) to display a speech bubble we checked the command's reference wrong and didn't bind (by modifying the reference) the bubble to a certain hero. So they just appeared randomly above the sprites what triggered the event, or even in worse places.
CGE2: Implement functions connected to inventory handling.

Also move closePocket() closer to the others and fix the stub message in busy().
CGE2: Implement snKeep().

Now the inventory system is (at least partially) working.
CGE2: Implement offUse().
CGE2: Implement inf().
CGE2: Comment out code and add TODO in switchScene().
CGE2: Implement showing the selected item in the inventory.

Now the selected item's picture is blinking until deselected.
CGE2: Implement Sprite::works().

Now Anna is also reachable/playable.
CGE2: Implement snMouse().
CGE2: Implement Hero::fun().
CGE2: Implement optionTouch().

Add stubs for called functions.
CGE2: Implement "quit menu".

Now the "main switch" on the menu panel is working.
Also move a couple of defines from cge2_main.h to cge2.h during the process.
CGE2: Avoid some signed/unsigned comparisons
CGE2: Reduce the scope of some variables