Adds a steel trapdoor. Textures were painted from scratch, and
inspired by the current Steel Door. Ownership on the trapdoor
works as expected, and so does the crafting recipe.
Playing stereo sounds positionally in OpenAL causes it to play
the sounds unattenuated - same volume for all distances. This
shouldn't happen, and makes door sounds unneccesarily loud from
very far away.
Convert all door samples to mono, 22kHz 64kbit.
Trimmed all door samples to remove lead, trail silence.
Rename in game.conf and documentation
Update game_api.txt documentation for bucket API and tree functions
Fix tab, space and comment formatting in game_api.txt
Rename in mod READMEs
Mirror the setup of a door placed next to any door, not just next to
a door of the same type. This is particularly useful where there are
multiple door types that have the same appearance, but one wants the
doors of a pair to have different behaviour in some other respect.
When a trapdoor is mounted upside down, to make its top surface flush
with the floor above when closed, it is necessary to have some way to
climb through the trapdoor node when it's open. Making it climbable
like a ladder satisfies this need. It is somewhat realistic, as a real
trapdoor can have a ladder segment mounted on one face. When the trapdoor
is mounted in its default orientation, making the bottom surface flush
with the ceiling below when closed, the climbability when open is not
strictly necessary, but is still a convenience.
