[>2.0] Bug : Misalignment of hires weapon sprites

[Warrex]

Note: This only happens in GZDoom >=2.0. ZDoom 2.71, ZDoom latest x64 SVN and GZDoom 1.8.10 are NOT affected.

Bug: GZDoom >=2.0. misaligns hires weapon sprites (empty space between weapon and bottom of the screen, see attached screenshot). All weapons are affected execpt for the following: chaingun, rocket launcher, BFG (at least there is no empty space).

1. Scale Doom weapon sprites to 3x (also tested with 4x and 9x) their original size using e.g. 2dimagefilter (https://code.google.com/p/2dimagefilter/).
2. Put the new sprites into a ./hires/sprites/ folder structure and zip to .pk3 file.
3. Launch GZDoom loading the .pk3 file.

I have also attached a .pk3 for Doom 2 with the upscaled weapon sprites as requested by Blzut3 and Graf Zahl.

[Graf Zahl]

There were a few issues with fixed point coordinate calculations. Doing those in floating point and making a small adjustment to the texture handling fixes this problem.