* 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()`.
This is to cut down on boilerplate code because these encode the virtual screen size in the mode parameter, making it unnecessary to specify a virtual size separately.
Avoid passing this anywhere in the client code. It should only be set right before rendering the 3D view and the only code using the base palette should be the 3D renderer and hud_drawsprite.
Also make the palette override CVARs 3D view only in debug mode.
