* In our older codebase before the input code was refactored, Exhumed's turning was broken and was only applying the base factor of 12, significantly slower than the other games.
* Upon doing some testing in PCExhumed, I noticed their turning was faster as when the counter meets its target, the turn value is shifted left by 2, effectively making it 48: b90417ed8e/source/exhumed/src/player.cpp (L336-L337)
* Removed this CVAR because of this.
* Reworked turning code so that pressing left+right together cancel each other out and that pressing both doesn't call `updateTurnHeldAmt(scaleAdjust)` twice.
* Redid turn averages factoring in Exhumed's speeds, rounded off values and stored in an enum for clarity.
* Remove unused `getincanglef()`.
* Remove unused `getincangleq16()`.
* In `PlayerHorizon` struct, clamp value when setting target in `__settarget()`, not each public `settarget()` overload.
* Rename `PlayerAngle` method `applylook()` to `applyinput()`.
* Rename `PlayerHorizon` method `sethorizon()` to `applyinput()`.
* In `PlayerHorizon::applylook()`, slightly clean return to centre code so it doesn't do math if already at 0.
* In `PlayerAngle::applylook()`, slightly clean rotscrnang/look_ang code so it doesn't do math if already at 0 and reposition where mouse input is applied so that if input is applied, the player never enters a spin.
* In `Duke3d::player_struct::apply_seasick()`, use `buildfang()` method instead of scaling float to BAM within function.
* Requested by users, really don't know why...
* Interpolation values are guarded by the CVAR.
* For Blood, integer truncation is employed just like original game.
* For all games where more precise sine/cosine math has been utilised, no changes have been made.
* Added in fca846272e to deal with signed adjustments but its just not needed.
* Made better use of `binangle`/`fixedhoriz` class getters and setters than before as well.
* Reduce code repetition.
* Clamp incoming horizon when using `settarget()` methods.
* Eliminate double calculation that was occurring in `processhelpers()`.
* Stop panning if underwater.
* Remove overload from PlayerHorizon from d32dcd5f8e that was causing problems for other games.
* Remove static bool `plrFalling` also from d32dcd5f8e and add `bIsFalling` to `Player` struct, hooking up with save code as well.
* Based on SW's implementation purely for its commentary, but includes a fix from Duke's.
* Allow disabling Duke's slopetilting via `cl_slopetilting` like SW.
* Sync PlayerHorizon's `settarget()` with changes to PlayerAngle's from 19d9e1a947.
* For each struct's `addadjustment()`, multiply value by unit there rather than always within `processhelpers()`.
* Properly use `xs_CRoundToUInt()` within PlayerAngle's `processhelpers()` method instead of the signed version.
* Use `abs()` within PlayerAngle's `processhelpers()` like PlayerHorizon's.
