Log Message:
Update to 8.31:

Release 8.31 06-July-2012
-------------------------

This is mainly a bug-fixing release, with a small number of developments:

. The JIT compiler now supports partial matching and the (*MARK) and
  (*COMMIT) verbs.

. PCRE_INFO_MAXLOOKBEHIND can be used to find the longest lookbehing in a
  pattern.

. There should be a performance improvement when using the heap instead of the
  stack for recursion.

. pcregrep can now be linked with libedit as an alternative to libreadline.

. pcregrep now has a --file-list option where the list of files to scan is
  given as a file.

. pcregrep now recognizes binary files and there are related options.

. The Unicode tables have been updated to 6.1.0.