os: Add 'Framebuffer::Session::sync_sigh'

The new framebuffer-session function allows a client to register a
handler for receiving display-synchronization events.
os: Make buffer size of 'Reporter' configurable
os: Refine Attached_rom_dataspace::update
os: Add Rect::contains() to geometry utils
os: Add Point::operator ==
nitpicker: Consider menubar for pointer reports

The pointer-report facility used to report the screen-absolute position
of the mouse pointer. For nitpicker clients, however, this position is
meaningless because their coordinate is always constrained to the area
below the menu bar. This patch offsets the reported position
accordingly.
Scout: Add DroidSans-Bold10 font as tff
Minimalistic decorator for window system
Generic resource monitor (WiP)
Simple desktop environment (WiP)
desktop: Add decorator_nitpicker, report_rom
desktop: local_reporter
desktop: window layouter
desktop: Handle hover reports from decorator
decorator: Report hover status
decorator: Report only when hover model changes
desktop: Propagate hover reports to layouter
desktop: Forward decorator user input to layouter
desktop: Permit slaves to use RM service

Needed to run it on non-Linux platforms.
desktop: Move, top for floating window layouter