graphlog: some testing for incoming and outgoing graphs

graphlog: import util module rather than selected functions

i18n: check format strings when building xx.mo files

i18n: add python-format comments to da.po

i18n: extract strings with xgettext The xgettext program knows about Python string formatting and will mark messages with a special "#, python-format" comment in the hg.pot file. When msgfmt compiles the file, it can check these messages to ensure that the translated string uses the same conversion specifiers as the original string. The pygettext program is still used to extract the docstrings.

Merge with stable

wire protocol: avoid infinite loop (issue1483)