Move page title generation into BoostVersion.
No need to check for 'false'.

Because BoostLibraries does it already.
Small improvements to some of the display functions.
Move much of library list implementation into class.

An attempt to structure the file a bit better. Actually makes the file a
bit bigger, but hopefully it will be a little easier to manage now.
Doesn't seem possible to have category_value 'all'.
More verbose filter function.

I used to be quite keen on dense conditions. Now I seem to be regretting
that.
Just stuff all the functions into the class.
Precalculate some of the link stuff.
No need to pass around categories now.
Clean up the final page display a bit.

At least I think it's clearer.