sidebar menu styled better

each entry got shorter height and line-height of 1 to become more
close-packed. additionally, they got deeper indent when nested to be
distinguished better.
interwiki separator color change

colored to be in line with surroundings.
changed menu method structure

* moved menu rendering code into a separate method.
* functions that were determining whether menu entries had to be removed
was moved into separate methods.
* now menu actions can handle revisions, which I forgot to add.