Collapsable categories

[mruegenberg]

The package listing is extremely long. Usually, when just browsing through the list, you know what category the package you are looking for is roughly located in.

Thus, to reduce clutter in the full package list, it should be possible to collapse categories. This should work similarly to the way the Haddock documentation index does this. (Including storing which categories are hidden, probably with a cookie.)

[dcoutts]

Or more generally, a complete rethink of the browsing interface (which may have to be tied to the rewrite of the tags feature)

[gbaz]

#551 should resolve this.