1. Get rid of TMCCUNIXPATH environment variable
1. Get rid of TMCCUNIXPATH environment variable

2. Support timeout in tmcc proxy, so proxy doesn't hang when it doesn't
   get a UDP reply from the master tmcd.  Unfortunately, the fast path
   here involved introducing a setjmp/longjmp, which I am not too thrilled
   about (worried about Windows support...)  There are other ways (e.g.,
   socket timeouts) to do this, but would have required significant overhaul
   of the code.

3. Clean up some minor, unimportant logic errors

nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome