Misc: Fix FTBFS, npc dialogue, turret bug, cleanups

Hello,

This branch fixes a bunch of miscellaneous bugs.  A quick rundown:

 1.) The FTBFS comes from trying to store a reference in a std::map, which according to The Internet™ is wrong? (IANAC++P) Only tested on OS X 10.6 w/ gcc 4.2.1.  

 2.) Remove an unused function. This could be skipped, and the function could be used instead. See the commit message.

3.) I'm not positive this is a bug, but I'm pretty sure the return was on the wrong line. Compare it to the smg turret code above.

4.) NPC dialogue options have been blank for months when compiled with LOCALIZE=0.  The problem was that positional arguments are being ignored under LOCALIZE=0, and the dialogue was being passed to rmp_format() with the args in the wrong order.  There could be similar bugs in the code, but I haven't had a chance to investigate yet.

5.) Update a comment for output.cpp:string_format().

Please let me know if you'd like me to make any adjustments / fixes.

Cheers,
Fitz