Add STRINGIFY macro. Use it where appropriate.
Don't force IP key/value pair into userinfo updates.

Game can only expect it to be valid in ClientConnect and
ClientUserinfoChanged that immediately follows, but not in subsequent
userinfo updates.
Pass extra connection params to game mod.

Add GMF_EXTRA_USERINFO feature. If supported, server passes all the
extra positional parameters to `connect' command to game mod.
Force use of old_origin by ‘cl_nolerp 2’.
Transparently compress large layouts.
Double layout buffer size.
Fix recursive CL_ParseServerMessage invocation.

Don't emit partial demo and GTV packets once svc_zpacket is parsed.
Extend layout syntax to support color.
Properly handle GMF_PROPERINUSE in MVD recorder.

Do the same thing as SV_BuildClientFrame does when deciding if entity is
active, to be fully conformant to GMF_PROPERINUSE extension.