SWORD25: Fix compilation
SWORD25: int -> int32 correctness
AVALANCHE: Add some more graphic functions
AVALANCHE: move some more functions to Graphics
AVALANCHE: Scrolls is now set to private
AVALANCHE: Rename Graphics to avoid confusion, add drawBackgroundSprite(), set _background private
BUILD: Fix libpng detection when compiled as shared library with zlib.

This was breaking AmigaOS4 builds for the porter as his libpng was built
as a shared library depending on zlib. This should be safe for static
builds as well.
AVALANCHE: Move code from Menu to Graphics
AVALANCHE: Rework calcHand, move another function to Graphics
SWORD25: Fix alpha/colormod blitting

This is a backport to sword25 of the wintermute commits
e9cbda135bbc822009ff311cad6e420fb23cff82 and 2141ad285e0200f4773726a13504f960e382f13e

Thanks to eriktorbjorn for noticing and testing.
TSAGE: Implemented proper R2R object/player shading
AVALANCHE: Set drawArc private
FULLPIPE: Implement MovGraph::calcDistance()
AVALANCHE: Move debug display of magic lines to debugger
WINTERMUTE: Do antialiased TT font rendering
WINTERMUTE: Fix typo in comment
AVALANCHE: Silent warnings reported by wjp
AVALANCHE: Fix more gcc warnings reported by wjp
Merge branch 'master' into zvision
BASE: Fix uninitialized type field in plugin base class. CID 1002938.