Add USE_INTERNAL_LIBS, a default for USE_INTERNAL_*

Linux distributions that want to link dependencies externally will
generally want to link (almost) every dependency externally; similarly,
minimal-dependency builds that want to use the embedded copies of
dependencies will generally want to do so for (almost) every dependency.
Make it easier to choose one of those by setting USE_INTERNAL_LIBS=0
or USE_INTERNAL_LIBS=1, respectively.

The default can still be overridden per-dependency; for instance,
"make USE_INTERNAL_LIBS=0 USE_INTERNAL_OPUS=1" will use the system
version of everything except Opus.
Centralize checks for Freetype, with a user override

This lets us find a library in a non-standard library directory
(via -L in the pkg-config metadata), and allows overrides similar to
the Autoconf convention, e.g.

    make FREETYPE_CFLAGS=-I/opt/freetype/include \
        FREETYPE_LIBS="-L/opt/freetype/lib -lfreetype"

If pkg-config didn't work, assume that Freetype is in the default
location.
Allow libcurl to be in a non-standard location on all platforms

We didn't add CURL_CFLAGS to CLIENT_CFLAGS on all platforms, and didn't
use CURL_LIBS at all, so if "pkg-config --libs" returned "-L... -lcurl"
or even "/.../libcurl.a", it wouldn't work.
Allow OpenAL to be in a non-standard location on all platforms

Similar to libcurl, we didn't use OPENAL_LIBS and assumed it was
always "-lopenal".
Allow system libjpeg to be in a non-standard location

It doesn't have pkg-config metadata (at least on Debian), so if the
user doesn't override it, assume normal system paths.
Find system zlib via user override, pkg-config or in standard locations
Look for system Vorbis, Opus and Ogg via pkg-config

As usual, the order of precedence is: user override, pkg-config,
or assume they're in standard locations.

In particular, Opus isn't in the default search path on Debian.
Find Speex via user override, pkg-config or default search path
Prevent the skip of the glyph if it does not fit
Merge pull request #5 from morturp/patch-1

Prevent the skip of the glyph if it does not fit
Free Team Arena fonts/fontImage_X.dat buffer

Caused temp memory to be present all the time, so Hunk_Alloc ignored memory low/high preference.

May have caused other issues as well.
Fix getting servers from and being listed on id's q3 master server

Use q3 master protocol when com_gamename is Quake3Arena (the default), otherwise use dpmaster protocol.
(bug #5984) Unload renderer lib
SDL Mouse Button clean up

Make 'b' variable an int so that key values more than 255 will work (not currently an issue in ioq3 afaik).
Use SDL_BUTTON_* for easier transition to SDL2.
(SDL2 doesn't have SDL_BUTTON_WHEELUP or SDL_BUTTON_WHEELDOWN, X1/X2 are different values.)
Remove unused models from server_t
Initial Xcode workspace & project support (4.6.3).
Updated .gitignore and ioquake3fe Xcode project.
Added Retina-enabled QUAKE III logo icon files.
Details in misc/xcode/xcode-readme.txt
Fix the speex Xcode project since it was missing its header search path.
Added "all game" and "all ioquake3" schemes to Xcode workspace so that they build properly.
out seems to be unnecessarily large for one byte per pixel
Merge pull request #6 from morturp/patch-2

out seems to be unnecessarily large for one byte per pixel