hgweb: reindent atom/changelogentry.tmpl It was mixing tabs and spaces, and not in a good way. Indent style of other atom entries seems to be 1 space per level, so let's apply it here as well.

hgweb: remove unused/nonexistent filelogentry from atom/map filelog in atom style uses changelogentry to show commits, and atom/filelogentry.tmpl doesn't even exist.

hgweb: remove unnecessary CDATA markup in atom/branchentry.tmpl Since content is of type "text" (and is already escaped), using a CDATA section is not required. Looks like this was just an artifact of copying things from rss style in add2f9ddcfb5, because other entries in atom style don't use CDATA in such places.