Remove unused items from RAWs. (Oktane, refined warp flasks, down)

Gone are the following, which were not used or createable anywhere:

    * Oktane juice
    * Refined warpstone flasks

Also gone is turning feathers into 'down'. Down beds already use feathers
directly, so creating down was a dead-end.

Commented-out magma and water bottles in item_z_orcfort have also been
removed; these are now permanently part of the main masterwork files.
Gun rebalance. All pistols have force/maxvel 25k, muskets 50k

See GH #5 and http://www.bay12forums.com/smf/index.php?topic=125628.msg4760039#msg4760039 .

I'm not sure if this is a great solution or not; 50k may bump maximum
velocity speeds in DF, so this may not have any gameplay change at all. On the
other hand, this could result in muskets being overpowered. Testing would be
lovely.
Merge branch 'master' into unified

* master:
  Gun rebalance. All pistols have force/maxvel 25k, muskets 50k
  Remove unused items from RAWs. (Oktane, refined warp flasks, down)