inlining SavedBattleGame::getTile()

it's the most-called method in the whole project
remove shade range check from shader
inline SavedBattleGame::getTileIndex() for getTile

for total inlining of getTile() codepath
don't malloc and free temp arrays in _zoomSurfaceY

not that this solves any major delay in that function but oh well...
optimized _zoomSurfaceY() for 2x and 4x cases

This covers the default resolution of 640x400 and the obvious next
choice of 1280x800. The new optimized functions use 64-bit integers
rather than reading pixels a byte at a time and writing them back
one byte a time. The result is an fps boost of up to x1.5. The optimized
functions also fall below TileEngine routines in CPU use according to
the callgrind profiler.
Revert "remove shade range check from shader"

This reverts commit 7f5100df39efa4bb51e9e20ffea04c65c9fd6a87.

I can't find any problems caused by the change but removing the change from the
"Standart" routine does cause problems so I can't really assume that shades
will be within the alloewed range apparently.
further work on optimized scaler routines

added 32-bit version of the functions; they're almost as good as the 64 ones!
tweaked 64-bit x4 scaler to reduce register spills, mostly unsuccessfully
Merge branch 'optimization_attempts' into recruit_aliens