Update version to 2.1.24

See merge request STJr/SRB2!495

# Conflicts:
#	debian-template/control
#	debian/changelog

Add GME to MSVC 10 solution

See merge request !448

Deploy OS X and Debian packages from Travis-CI

See merge request !449

# Conflicts:
#	.travis.yml

Flashpals on screenshots

See merge request STJr/SRB2!492

Fix SIGSEGV from sending lindefs/sidedefs in savegame due to duplicated lines.

See merge request !490

Set modifiers in a non-reactive manner

See merge request STJr/SRB2!456

Don't skip frames when connecting or paused

See merge request !489

This reverts commit 7ac0a8b4.

Alias recursion hotfix 2

See merge request STJr/SRB2!482

Fix music load lag by reverting tag changes

See merge request !486

Ban IP command

See merge request !460

Don't count down wait timer when executing a command line

See merge request !483

OpenGL Sprite Billboarding

See merge request !485

add parentheses around these conditions to fix sloped lights cutting out lights on FOF walls for apparently no reason

not making a merge request because this is so laughably stupidly simple

Don't enable UPnP support if NONET is defined.

See merge request !484

Because songs without this tag will skiplag when loading.

1. It's slow, 2. It's incorrect

Should work on both normal and precipitation sprites.
Sprites that are split by lighting should work correctly.

Detect infinite alias self-recursion mixed with other commands, such as in the case of `alias a "echo test; a"; a`.

(Unfortunately, this does not work if "wait" is used instead of "echo", but oh well)