Widespread API changes
Add some mark_as_advanced() statements to CMake build files
Improve platform-specific code in build files
Remote/Input becomes Controller, udev.cc/.h become hal.cc/.h
Improve Monitor API with flag MONITOR_TIMEOUT
Initial Mapper implementation (useless identity for now)
Revert Monitor timeout code (bad idea)
Use timerfd instead of eventfd inside Mapper
Cosmetic changes and small fixes