Apply "small match" rules to 2v2 games

Originally, a 1v1 was the only special case for an Arena: Respawn
match. This commit applies those same rules - overheal on capture - to
a 2v2 match as well.
Do not apply the LMS critboost unless the LMS is outnumbered 3 to 1

If the opposing team has fewer than three players, the LMS will not
receive a critboost.
arena_capricorn: Fix late arrival of control point
arena_dropdown: Remove map-spanning trigger_multiple brushes

These map-spanning trigger_multiples were originally designed to
detect if one team or the other was completely dead, then fire the end
sequence accordingly.

Since the end sequence hooks have been transferred to OnWonByTeam1 and
OnWonByTeam2 (as they should be) these trigger_multiples are
unnecessary, and actively damaging to the KOTH door-opening logic
employed in a future commit.
Add KOTH Stripper: Source configuration file

It is recommended to symlink the names of any KOTH maps in rotation to
koth.cfg. This config file performs two functions: 1) replacing the
tf_logic_koth entity with a tf_logic_arena; 2) reducing all health
packs by a factor of one (such that large health packs become medium,
and medium health packs become small).

The health pack downgrade "logic," such as it is, may be recreated more
intelligently in the plugin itself in future. For now it remains
necessary to have some form of health reduction, lest the KOTH maps
fail to play like Arena maps.
Fix doors opening early on KOTH maps

This commit introduces a significant number of entity-related utilities
required to detect a "spawn" door from a regular func_door.

In the 40+ Arena and KOTH maps tested, the spawn door detection logic
has worked well, forcing the appropriate func_doors open on round
start, and leaving spawns vulnerable as they would be in an Arena
match.

For a more in-depth discussion of the spawn door detection logic, refer
to this post on the official Arena: Respawn Steam group discussion
board: http://goo.gl/7PJxea
Add KOTH maps to mapcycle.txt

This commit adds several recommended KOTH maps for Arena: Respawn play
and removes 4 Arena maps that have not proven to play well in pub
servers.