* Automatically run --gettime the first time ikiwiki is run on
a given srcdir.
* Optimise --gettime for git, so it's appropriatly screamingly
fast. (This could be done for other backends too.)
* However, --gettime for git no longer follows renames.
* Use above to fix up timestamps on docwiki, as well as ensure that
timestamps on basewiki files shipped in the deb are sane.
4291f2e3d7 made
just setting underlaydir not enough to change
where other underlays are loaded from. While generally
a good thing, that broke building of the docwiki
from the source tree, because underlaydirbase
was not pointing there.
Setting underlaydirbase in the setup file is a solution,
albeit slightly hacky (since the variable is undocumented and internal).