also don't change POT creation date when rewriting a po file, update
Po-Revision instead.
When creating templates, put X-Accelerator before X-Generator (like
pootle would order it)

Change-Id: I7fec4cb1c50e27b87decd9a892de3f01a02253ed
Reviewed-on: https://gerrit.libreoffice.org/63416
Tested-by: Jenkins
Reviewed-by: Christian Lohmaier <lohmaier+LibreOffice@googlemail.com>