Primarily aimed at reducing the size of the old 'man' (now: files)
table, using smaller integers to refer to man contents and text fields,
and storing a shorthash as an integer for quick lookups. This better
normalization also removes the need to keep a separate 'man_index' cache
for the search function.
The old schema wasn't necessarily bad, but I was in the mood for some
optimizations. And a little cleanup.
Prolly introduces a bunch of new bugs, I haven't tested this too well.