The local history interface now reports errors to its callers isntead
of inconsistantly waning the user occasionally on error.
The documentation comemhts were also updated to match reality
The browser window common initialisation code returns error codes which
were being ignored. The errors were additionally being reported via
warn_user in inappropriate places within browser history construction.
The netsurf core is driven from numerous operation tables most of
which are now set through a common netsurf_register() interface. The
font and plotting interfaces are currently separate and unlike all the
other operation tables are modified for differing contexts.
This change moves the font operations alongside all the other
operations table and remove unnecessary interaction with the renderers
font internals. Further this also removes the need for css internals
to be visible in frontends.
