From javscript C functions cannot be called, but signals
are available through the GObject type system. So
we allow javascript to call action signals like functions.
At the same time we modify a few browser functions, so
that they are functions that are available as signals.
The new singleton holds the shared settings and trash. It is
further more used to keep track of all open windows and quits
when the last window was closed. It also watches the focus in
case you need something like a "current" browser.