mmap/mmunmap and file cleanup from upstream issues
Fix unmmapFile on BSD/Mac
Document csearch flags better
Shortcut max file size check
Added -indexpath flag for overriding $CSEARCHINDEX
Added some Mac OS X specific path ignores
Don't add invalid utf-8 trigram + minor code rearrange
csearch: Added the -m MAXCOUNT option
Added Bittorrent Sync and Dropbox cache/metadata to ignores
index: fix index merging on windows

Rename fails on Windows if destination exists.

The following sequence will now correctly work:

  $ cindex a
  $ cindex b

instead of silently failing to update the index with b content.