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>

ui-repolist.c

@@ -30,7 +30,7 @@ void cgit_print_repolist(struct cacheitem *item)
 		html_txt(repo->name);
 		html_link_close();
 		html("</td><td>");
-		html_txt(repo->desc);
+		html_ntxt(cgit_max_repodesc_len, repo->desc);
 		html("</td><td>");
 		html_txt(repo->owner);
 		html("</td><td>");