Linux binary build

[jdolan]

We should provide a Linux binary build (with bundled updater), similarly to how we package the game for OS X.

I've already stubbed out a Makefile for the Linux build that mirrors the OS X release management targets; see quake2world/trunk/linux/Makefile.

r1510 adds support to the game filesystem for loading resources (e.g. game.so) from quake2world/bin/default and quake2world/default, provided the game was started from quake2world/bin/quake2world.

The work remaining is to convince the binary to load shared libraries from a relative path. This should be doable by adding something like --rpath=\$ORIGIN../lib to HOST_LD_FLAGS in configure.in.

Parsing the output of ld should provide a decent baseline for determining the shared libraries that actually need to be bundled with the game.

[jdolan]

r1659, r1669, r1672 were all committed against this. The Linux build works a lot like the Mac build, and runs on most recent 64 bit distros. Users are expected to install libSDL-image, libSDL-mixer, libcurl, and their video driver through their package manager. Whoever updates the Linux build should take care to not build against ncurses and MySQL.