obsolete: pass only new markers to _checkinvalidmarkers() We will soon delay populating precursors until we have to. To prepare for that, make _checkinvalidmarkers() scan for a nullid precursor in the list of new markers instead of the (currently) cheaper 'if nullid in precursors' check.

obsolete: extract helpers from _load() In preparation for making the successors, precursors, and children dictionaries lazily populated, break up _load() into one function for adding markers to each dictionary.

test-gendoc: require gettext If the gettext utilities aren't installed, there is no way to make the translations. This causes the gettext client to fall back to the untranslated message, which triggers "** NOTHING TRANSLATED **" errors and a test failure.

hgweb: use css margin instead of empty <p> before diffstat table The <p> elements were used to create an empty space between the diffstat link and the diffstat table, but they don't have any semantic meaning, so it is better to use css instead. Default margins for <p> elements can differ depending on the browser, but usually the margin is 1em (exceptions are IE 6 and 7 with 14pt, which is comparable). The css rule sets top margin to 1em. This change is a "better version" of 70cfa7e1611b, where <p> elements were simply properly closed.