* 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()`.
Timer values in interface code are undefined, these should not access anything that changes at real time.
Also use smoothratio to do the calculation in frame time, not tic time.
This timer only gets incremented by the main game ticker when the playsim is running.
This timer gets used for all playsim-related timing and animations so that these are decoupled from imprecisions in the global timer.
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.
* Build timer still requires initialisation due to multiple `timerSetCallback()` that still need to work.
# Conflicts:
# source/core/menu/menu.cpp
# source/games/duke/src/game.cpp
* Current setup was broken and unusable.
* Fixed interpolation issues.
* Only call `GetInput()` at frame-rate when `cl_syncinput` is 0.
* Create `oq16look_ang` and interpolate it for enhanced smoothness.
* Always reset `horizAngleAdjust` and `horizSkew` in `processinput_d()`.
* Don't pre-scale `sb_avel` in `processinput_d()` and `processinput_r()`.
* Promote `p->angvel` from short to fixed_t.
* Don't descale `sync[snum].q16horz` in `processinput_d()` and `processinput_r()`.
* Ensure `false` bool is provided to `sethorizon()` call in `processinput_d()` and `processinput_r()`.
* Reset `p->q16angvel` in `resetplayerstats()`.
The checks for game pause were totally inconsistent, so now there is a utility function that tells whether the game is supposed to run or not.
pause can also take 3 values now - 0 for no pause, 1 for pause from opening the menu or console or 2 for hitting the pause button.
