* 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 removes most of the InputState class because it is no longer used.
The only remaining places still checking scan codes are the modifiers for sizeup and sizedown.
All the rest was remapped to safer methods. The multiplayer taunts are currently inoperable, they will need support of shift-bindings to get proper support.
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.
