Add textmap pitch and roll parsing, and mobj pitch and roll variables.

See merge request !882

Add mapthing scale support

See merge request !883

Add mapthing scale support; fields scale, scalex and scaley set the only mapthing scale field alike.

No more magic numbers for linedef arg values in UDMF

See merge request !881

Make the Spawn Object linedef executor able to set the object's angle.

See merge request !877

The rule for PACKETVERSION is too confusing, it's also too hard to unify formats

See merge request !875

A tangible mechanism to disable Continues

See merge request STJr/SRB2!865

srb2:// server URLs

See merge request !858

UDMF colormaps

See merge request !855

Remove faulty code from T_MovePlane()

See merge request !876

Remove the disabled/broken bridge thinker code

See merge request !879

Actually remove the entire code block in T_MovePlane(), and remove line_t.tagline as it served no other purpose.

# Conflicts:
#	src/lua_hooklib.c

PK3: Proper ignorance for file comments/extra data

See merge request !761

Fix MD2 rollangle in reverse gravity

See merge request !818

OGL horizon lines

See merge request !861

ExecCfg fixes

See merge request !821