Restructure entrykvs

[lordfeck]

Currently we heap all entries under %entryKvs like follows:

$entryKvs{KEY_NAME} => { ... }

Each entry exists directly under here. The category name is a field for the entry.

We could optimise performance and readability if we restructured storage to work as follows:

$entryKvs =>$categoryName => $entry

We could simply call 'keys' for the category name nested under the entrykvs, this would return a list of categories for easier processing. Likewise we could get all the entries for each category. This saves effort in the long run and thus seems more like True Perl (TM).

[lordfeck]

We look up entries by key name alone in more than a few places, so shelve this for now unless performance becomes a demand (i.e. processing thousands of entries) and we're then checking every entry for a matching category