Add log filtering by path and link to it from tree view

This enables path-filtering in log-view, and adds a link per entry in
tree-view to show the log for each file/directory.

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

cgit.css

@@ -189,6 +189,11 @@ td.filesize {
 	font-family: monospace;
 }
 
+td.links {
+	font-size: 80%;
+	padding-left: 2em;
+}
+
 td.filemode {
 	font-family: monospace;
 }