Remove extra magnitude from magic texture mapping values

- These used to be fixed point, but now they're floating point, so the
  excess magnitude is unneeded.
Remove DepthScale and DepthOrg from FWallTmapVals
- fixed: With P_ExplodeMissile now working properly it is no longer valid to terminate a looping sound in a missile's death state because it now gets called after the death sound has been started.
- fixed: The demo buffer was allocated with conflicting methods, because M_ReadFile used new whereas the rest of the demo code assumed malloc. Added a new M_ReadFileMalloc function to handle this case without rewriting other things.
- Fix the division by 0, improve comments.

- Avoid doing the division if the result would be outside the ]0,1<<24[ range:
-- if the numerator is nonpositive, ie <=0, truncate the result to 0,
-- if the numerator is greater or equal than the denominator, the result will be outside the allowed range, hence truncate the result to 1<<24.
-- otherwise, the result will be inside the range. Knowing that the denominator is greater than the numerator, if the numerator has the last 24 bits non zero, the denominator can't be less than 1<<24, hence the denominator won't be truncated to 0.
- Add comment details to help who doesn't know math. Big deal!
Merge branch 'slope64_comment' of https://github.com/edward-san/zdoom
- Add new function for the new slope calculations.

Fixed also two MSVC warnings.
- Oops comment typo.
- Added flags for A_Fade functions:
- FTF_REMOVE: Removes the actor when the alpha hits a certain level.
- - A_FadeIn - 1.0
- - A_FadeOut - 0.0
- - A_FadeTo - Alpha target level reached
- FTF_CLAMP: Automatically fixes the alpha so it won't leave the range [0.0, 1.0].
Merge branch 'fade' of https://github.com/MajorCooke/zdoom
opl3 emulator update
- Added: Boolean to specify if A_Raise functions should perform CopyFriendliness based upon who raised it. By default, this is false.
Merge branch 'raise' of https://github.com/MajorCooke/zdoom
Fixed message duplication in logs

- Any printed hud messages would have duplicate entries in logs.
- Moved bot specific functions into DBot.
Merge branch 'BotFunctions' of https://github.com/ChillyDoom/zdoom
Destroy mod-created CVars when 'restart' is invoked
Fixed weapon drawing rules to account for the death camera [backported from gzdoom], also fixed drawing rules for crosshair
Merge branch 'bug-47011' of https://github.com/kevans91/zdoom
Fixed SV_SAMESPAWNSPOT behavior -- When enabled, use the p->mo->z. Otherwise, rely on ONCEILINGZ/FLOATRANDZ/ONFLOORZ w/ or w/o UsePlayerStartZ as previously done