When moving the mouse over a NPC, the cursor would change accordingly, even

... though the NPC was hidden by FoW, so we were leaking their locations

Signed-off-by: Jaka Kranjc <lynxlupodian@users.sourceforge.net>
cmake: only install the shaders if opengl will be built
switch UNMOVABLE to UNDROPPABLE only when the item is picked up

Fixes not being able to pick up the portal key in Irenicus' Dungeon.
check for non-movable items in CalculateWeight again

Fixes regressions concerning internal "items" being dropped.
add new animation type for Melissan (MMEL)