Fix false file error reporting

See merge request !514

Make FixedRem less laggy by just using the modulo operator.

See merge request !503

Fix MF_NOCLIPTHING

See merge request !467

Lua: Fix some errors not working properly.

See merge request !510

Use M_FileError to return the proper error description, or "end-of-file".

Since the enum type is implementation-defined, and could be either signed or unsigned.

Compare the file name only for real

See merge request STJr/SRB2!511

Calling all Lua consvars

See merge request STJr/SRB2!509

CL_SendRequestFile prepends the path for each file.

* Make sure the consvar's properties are all initialised to zeros as defaults
* Error if the consvar is not given a name
* Error if the consvar has CV_CALL but no call function
* Error if the consvar has CV_NOINIT but not CV_CALL

Update version to 2.1.25

See merge request !507

Fix an exploit where players could steal the final hash of a login

See merge request !508

PolyObject crush hotfix

See merge request !506

Use P_MobjInsidePolyobj instead of P_MobjTouchingPolyobj, so that you can be crushed by the polyobject's middle rather than just its edges

PolyObject fixes backport

See merge request STJr/SRB2!505

After looking at the FOF part of P_LineOpening for a while I now realise many of these variables aren't even necessary, so I removed them all.

(Naturally I did the same to the camera equivalent)

# Conflicts:
#	src/p_maputl.c

Edit a lot of the rest of the polyobject-related code in P_LineOpening to make more sense and be more optimised.

* If you collide with a line belonging to a polyobject, you should NEVER have to care about any FOFs that might be present in either sector of the linedef. This could lead to colliding with ghostly FOFs that aren't actually there or something dumb, if someone decided to give either of the polyobject's control sectors FOFs for some reason. We don't want that, obviously.
* Polyobjects without POF_CLIPPLANE apparently are supposed to have a top and bottom "physical" height of value INT32_MAX and _MIN respectively, according to P_CheckPosition ...let's be consistent with this.
* Finally, there is no more need for that back = front nonsense hack anymore with my changes made.

# Conflicts:
#	src/p_maputl.c