many small changes to templater.
get string code to parse escapes. uses eval now, should parse strings
itself soon.
let caller check if fragment is defined using "in".
make templatepath take optional file name.
default = "changelog"
header = header-rss.tmpl
changelog = changelog-rss.tmpl
changelogentry = changelogentry-rss.tmpl
filelog = filelog-rss.tmpl
filelogentry = filelogentry-rss.tmpl
tags = tags-rss.tmpl
tagentry = tagentry-rss.tmpl