make mercurial look in more places for config files. now it searches <install dir>/etc/mercurial, /etc/mercurial, and user hgrc. this allows site-wide configuration to be shared over automounted nfs partition, instead of chenging on every system. option of having local configuration on every system remains. old code for searching /etc/mercurial/hgrc.d never worked, this code is tested and works.

default = "changelog"
header = header-rss.tmpl
changelog = changelog-rss.tmpl
changelogentry = changelogentry-rss.tmpl
filelog = filelog-rss.tmpl
filelogentry = filelogentry-rss.tmpl