Capture changes - Engis now capture from outside. Added classic (legacy)...

... capturable traits.

Changes made are:

* Capture classes no longer require the Building trait.
* Removed "change owner to neutral" when capturing, and split the current Capturable logic into two pieces: Capturable and LegacyCapturable.
* RA Engineers use Capturable (RA Sniper uses LegacyCapturable on Church)
* Cnc Engineers use LegacyCapturable

Capturable
* Engineers take 15 seconds to capture buildings, and do so from the outside. Engi and the building will flash while capturing, and the progress bar is shown.

LegacyCapturable
* Engineers will sabotage or enter a building, if it has low enough health, to capture it
* In Cnc, sending two engineers to one building will result in the building being dropped to 50% health, then captured. Neutral buildings require no sabotage (ever).

YAML (Capturable)
* Capture duration (attached to building)
* Destroy engi after cap (attached to engi)

YAML (LegacyCapturable)
* Capture HP threshold (attached to building)
* Sabotage damage (attached to engi)

YAML (Both)
* Capture types=building,vehicle,etc
* AllowAllies/AllowNeutral/AllowEnemies