Add "pull-tx" rule in Makefile

The rule pulls all translations, then formats them to avoid style
changes. After running the rule you can check what changed using
your revision control system tools (git diff here).

The commit also updates the only change that was pulled by the rule
itself.

git-svn-id: http://svn.osgeo.org/postgis/trunk@13084 b70326c6-7e19-0410-871a-916f4a2858ee