fix sanitizeRegex to not strip "dots"

sanitizeRegex was stripping dots in permalinks when generating
RenderIndexes (noted during feed/rss generation).

permalink was being set to `.../indexxml` instead of `.../index.xml`.

Adding "dot" to the regex whitelist fixed the issue.
move "dot" in regex to avoid it being part of a range
Merge pull request #31 from cactus/issue-31

sanitizeRegex chopping dots