This is based on the rolling hashes code from
http://cgit.freedesktop.org/~krh/weston/log/?h=remote
It works by incrementally calculating hashes for every 32x32 block
in each frame sent, and then refering back to such blocks when
encoding the next frame. This means we detect when a block matches
an existing block in the previous frame in a different position.
This is great for detecting scrolling, which we need now that
the gdk level scrolling is neutered.
If we're going to run off the end due to an invalid message,
we're going to run off the end. We'll protect this by doing
proper bounds checking in the future, but the malloc gives
us nothing for now.
-Don't include unistd.h unconditionally as it's not available in Visual
Studio, but include io.h where necessary.
-Avoid C99isms, and use _chsize_s in place of ftruncate when unistd.h is
not available (as in the case of Visual Studio)
This way we don't have to reopen all the time for pure updates,
and we can immediately unlink the shm file to avoid "leaking" them
on improper shutdown.
We don't want to update the window size on configure event, only
the position, as the size is client side controlled. We were
updating to an old size during resizes which causes us to send
surfaces of the wrong size to the daemon.
With this we always roundtrip position change to the webbrowser.
This avoids conflicts when things change from both directions (app and user).
Also, we fake configure evens when there is no web client to ensure
apps get the events.
This (shouldn't) change any behaviour, but it moves the
webserver parts to a separate file, making the broadway display file
smaller and preparing for later separating out the server to its own
process.
