Implement std::hash for Str::StringRef
Add framework/Resource and use it for audio/Sample

This is somewhat WIP, there are a few blocking TODOs,
especially the one near the declaration of Manger::Register
Add the S_{Begin/End}Registration syscalls and use them in cgame
Resource: introduce a Handle WIP for c&c
Fix compilation of std::hash<Str::StringRef>
Fix a stupid 'optimization' in std::hash<Str::StringRef>
Update the doc of Resources for Handles
Build unified client with rendererGL.
Remove old renderer files.
Merge branch 'master' into engine-upgrade/sound_resources
Fix the TTY client build
Resource: improvements to Resource made when trying to use it in the renderer
Merge tag 'v0.24.1' into archlinux

Alpha 24, Point release 1
Add an option to force download-pk3-torrent.sh to download a specific version.
basepak.sh: fix .pk3 optimisation and script termination.
Merge branch 'engine-upgrade/sound_resources'
Implement the FindPak syscall in NaCl
Log: Introduce the PRINT level and use it for console specific prints

This is a first try and is a bit ugly. The PRINT level is like
NOTICE except that a console can ask to be the sole receiver for
PRINTs (so that most commands output will stay on that console only)
So this commit:
 * adds a PRINT level and add the level to Log::Event
 * adds an entry point to Log to change the target for PRINTs
(no target specified = all console)
 * implement that console lock for commands and completion in consoles

The problem is that Com_Printf uses Cmd::GetEnv()->Print() which will
use Print() so commands like /map may end up putting everything in a
single console even though that's not what we want (some things should)
use NOTICE.
Small fixes to the log changes
Deal with iqm models that have no animations.

The engine used to bomb out at various places, no at least the base pose
of the model is drawn.