First, the files need to be splitted to many smaller ones, handling specific
things.  Like select.c handling <select> stuff and menus (lying here already,
but I wasn't yet brave enough to commit it), forms stuff, frames stuff etc.

Then, the code needs also to be cleaned up massively, so it'll be clear to
mere mortal how it works and what it does actually :).

And then, it needs to be rewritten ;). This HTML engine will be kept in
parallel to the new one (ELusive, src/elusive/) until ELusive will be stable
enough and will contain complete superset of functionality of the current HTML
engine (Mikulas').