This allows us to build with libdecor enabled as the selection to use it
is decided upon at runtime if the compositor `gnome-shell` is detected.
If the libdecor development headers are installed, by default it will
now be compiled in unless overridden by the user at compile time.
Currently, we scale the desktop up to the next largest integer, and rely on
the wayland compositor to scale it back down to the correct size.
This is obviously undesirable.
In this commit, we attempt to detect the actual fractional scaling by finding
the current active mode in wl_output, and dividing it by the logical screen
size reported by xdg_output, taking into consideration screen rotation.
We then use wp_viewporter to set the exact buffer and viewport sizes if
fractional scaling is needed.
Currently, we dispatch the events on the wayland display server ourselves.
This is fine when using the cairo backend of libdecor, as it does the same
thign we do, but other backends may require other things to be dispatched.
This commit lets libdecor dispatch events instead through libdecor_get_fd
and libdecor_dispatch, which should hopefully makes things less sketchy.
The Wayland display server is getting unwieldy due to the sheer size.
To make it easier to edit in the future, I split it into many components
based on logical boundaries.
