slightly massive changes to sprite drawing routines.

adjusts dual wielding routine to properly represent dual wielding two of the
same weapon.

if two dual-handed weapons are held, choose the one currently being used
to display.

rifles will now be held properly, with the right arm "in front" of the gun,
as a human being would hold a rifle.

if a pistol and a 2 handed weapon are used, represent both when firing.
- this includes holding a rifle the left hand.
fix reaper gravity

reapers fallin on reapers and gravity and oh god no, just no.

removed some redundant code, fixed some code to account for stupid
large units, replaced vector with list to avoid NPE on our iterator.
fix for issue 24

prevents the crash by handling the iterator better.
adjust horizontal blockage routine

to handle bigwall integers for explosions and LOS functions.

also fix up the footstep sounds.
Factor the Z into throws.
fix explosion gravity

since we can potentially destroy ceilings, we should apply gravity to the
tile above as well.

also renames the function because the applyGravity function doesn't just
affect items.
end dogfight if minimized and UFO outpaces the craft.

fix music switching issue.
stop the escape timer when minimized.
Use autoconf macros to search for opengl.
Whitespace
Shaders do not require executable bit.
Make "make distcheck" work again

If this command is run prior release it verifies that the source can
be built and installed. Which should avoid having broken tarball like
with 0.9.0 release.
Cleanup the ebuild.
Generate and install man page
Package icons and desktop file.
Fix variable name typo and copyright year.
Fix typo in desktop file to pass validation
small fix in explosions
Merge pull request #487 from scarabeusiv/master

Various autotools fixes
fix for some silacoid stuff.

better handling for the SPECAB_BURNFLOOR basically.
sets fires, does the right amount of damage to the right spot instead of
flat out destroying everything it touches.
adds fire immunity to units with this ability.
tee hee, terrain level is negative.