hgweb.cgi and hgwebdir.cgi fixes/cleanups for user configurable parts: - "import os" was missing in hgwebdir.cgi, added to comments for both script. - HGENCODING has to be set before importing hgweb, otherwise you'll get mixed encoding in changelog vs. file content/diffs. - "import sys" is only needed when changing sys.path - document purpose of cgitb.

foo renamed from bar:26d3ca0dfd18e44d796b564e38dd173c9668d3a9
   rev    offset  length   base linkrev nodeid       p1           p2
     0         0       6      0       0 26d3ca0dfd18 000000000000 000000000000
     1         6       7      1       1 d267bddd54f7 26d3ca0dfd18 000000000000