Merge branch 'monster's-miscellaneous-meddling' into 'master'

Monster's miscellaneous meddling

A miscellaneous assortment of code-cleanup and other changes, plus fixing up SRB2's tangent array so it behaves more as expected (especially on the Lua side).

More specific details of the changes:

(MUST-HAVE CHANGES)
* `finetangent[]` has been entirely redone in the same manner as finesine/finecosine.
* Lua's tan() function shifts `finetangent[]` results by `ANGLE_90` to get what you EXPECT it to return (e.g. `tan(0)` actually returns 0 now). This means finetangent itself doesn't need to change its general arrangment, this only affects Lua specifically.
* Lua's tan() function now also doesn't go out of `finetangent[]`'s bounds at all. Before, `tan(ANGLE_180)` through `tan(ANGLE_MAX)` and such would just give you values unrelated to the array in question, which was clearly a bad thing.

(CAN PROBABLY LIVE WITHOUT?)
* `finecosine`'s definition moved from r_main.c to tables.c.
* Created `P_CheckTimeLimit` for `cv_timelimit`, much like `cv_pointlimit` has `P_CheckPointLimit`. It cleans up `P_UpdateSpecials` a bit at least.
* Some code cleanup relating to translucency maps - these are kind of unimportant, I was about to stop `FF_TRANSMASK` being used everywhere, but this was apparently a bad idea so I backtracked a bit.
* Re-added `_MSC_VER` check around MSVC-specific code in doomtype.h, in case it wasn't defined (and `__OS2__` was). Also left a comment there regarding `__BYTEBOOL__`.
* Fixed an apparent copy+paste goofup in `joyaxis_cons_t[]` for the Wii-specific code.

See merge request !10