Revert "- `xs_Float.h`: Add `getint()` getter to `_xs_doubleints` struct."
Revert "- SW: When adjusting horizon in `DoPlayerDeathHoriz()`, just use integer horizon values and not Q16.16."
Revert "- Duke (RR): Clean up some unnecessary `FixedToFloat()` usage with the `fixedhoriz` `asbuildf()` method."
Revert "- `binaryangle.h`: Use `constexpr` on inline functions where it was previously not possible to do so."
Revert "- `m_fixed.h`: Use `constexpr` on inline functions where it was previously not possible to do so."
Revert "- `xs_Float.h`: Convert header to `constexpr`."
This does nor work as it violates the constexpr rules for unions. The code will error out on compilation for accessing an inactive member of a union.
For any mainstream platform that is totally irrelevant and besides, in C++20 it will be well defined and all current compilers on the relevant platforms treat it accordingly.
This is not worth deoptimizing the code.
Use constexpr where possible to allow using these function in static initializers.
Avoid dividing by constant values. Better multiply with the inverse which is quite a bit faster.
* 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()`.
