Correctly evaluate if a 3D floor starts above the ceiling/below the ground when testing against them, that way they won't be ignored on line hit. This fixes a lot of edge cases with ramps in particular.
* Feature-complete isometric mode fork.
* Dithered transparency condition tweaks.
* Dithered transparency for non-corpse monsters only (and missiles).
* SpectatorCamera vertical shift.
* Including math.h in hw_sprites.cpp to keep visual studio happy (it couldn't find M_SQRT2 definition).
* Defining MY_SQRT2 in hw_sprites.cpp to keep visual studio happy (it couldn't find M_SQRT2 definition).
* Defining MY_SQRT2 in r_utility.cpp also to keep visual studio happy.
* retrigger checks
* Have correct sprite angle-frame face the camera with orthographic projection enabled.
* Dithered Transparency now works properly on 3D floors. Moved that dither-trans flag setting code within hw_bsp.cpp to handle double-processing of linedefs. Added helper functions to FRenderViewpoint class 'bool IsOrtho()' and 'bool IsAllowedOoB()' to clean up checks everywhere in the code.
* Fixed indents. Added bbox property to subsector struct and use it instead of BSP nodes and Clippers (creating a bbox around viewpoint and checking for overlap) in orthographic mode when no fog of war is active. Turns out to be much faster. Though you need really big maps (Winter's Fury MAP01) to see a difference in fps.
* Non-linux checks don't like uint. Changed to unsigned int.
* Small change of a float to camera.zs. Ignore for testing. Should make no difference.
* Update actor.h to remain mergeable
RF2_NOMIPMAP was introduced, so I had to displace RF_ISOMETRICSPRITES to next bit.
As it currently stood, only traces that never found anything in traversal had their distance and final position corrected.
Meanwhile, traces that skipped everything would return the distance and position of the last thing they crossed instead.
This change makes both cases consistent by "filling out" the remainder of the trace line for the latter.
