Restrict length of repo description on repolist page

If any repo has a very long description, all repos suffer since the
repo-links in the right-most column gets pushed out of sight.

Fix it by introducing max-repodesc-length parameter in cgitrc, and default
to 60 chars.

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

cgitrc

@@ -51,6 +51,10 @@
 #module-link=./?repo=%s&page=commit&id=%s
 
 
+## Number of chars shown of repo description (in repolist view)
+#max-repodesc-length=60
+
+
 ## Number of chars shown of commit subject message (in log view)
 #max-message-length=60