* Remove fix16.h/cpp and utilise library from m_fixed.h.
* Extend m_fixed.h with two inline functions for int to/from float operations.
* Replace fix16_floor operations with those from xs_Float.h
* Replace multiple Q16.16 conversions from 0 to just be 0.
* Replaced all found in-game bit-shifts and multiplications/divisions with inline functions from m_fixed.h
* Replaced many casts of FRACUNIT as double in SW's panel.cpp as it is converted to double by way of type promotion.
* Fixed missed precision fixes in SW's panel.cpp where some types weren't declared correctly.
* Replaced 100+ `Cos()/Sin() >> 16` operations for Blood with inline functions `CosScale16()/SinScale16()`.
In particular this means to remove the option to disable widescreen aspect ratios. The way this was handled makes no sense with the current render backend.
The aspect ratio code will have to be redone entirely to properly obey the backend's settings.
* rewrote all uses of timerSetCallback. Most were unnecessary or long obsolete, the sound updates need to run per frame, not per tic and the UI tickers need to be handled in the main loop anyway.
* Use a more precise timer to animate the menu transition.
* uncouple other menu animations from the game timer.
* Returns a true double result.
* Also supports fractional input for fractional input. That is, if `sintable[1]` = 50 and `sintable[2]` = 100, `calcSinTableValue(1.5)` = 75.
* Increased precision of `BANG2RAD` define to use double and not float.
* As such, revert addition of `sintablef[]`.
* Serves no purpose in Raze or GZDoom and appears to only have been added to the backend to facilitate the older interpolation code that was excised in 893686709b.
- delete some voxel code that's software rendering only.
- apply Big Endian byte swapping for SFXs, as well, now that this no longer involves hacking the file system cache.
The entire method at use here is essentially not correct. Interpolation should be handled independently of the game timer directly based on the underlying clock, like in ZDoom.
There's interpolation bugs in the Build games that cannot be fixed if totalclock is used for it, but if we use something else we do not need a fractional totalclock.
* Changes performed in 0bd460d9e3 didn't take into account xdimenscale and viewingrangerecip like the days of old and this wasn't picked up in d80a32d379 or d80a32d379, where the applied fixes only appeared to work because they worked for me at 2560x1440p.
