tkbio: more signal fixing, timer fixing
- preserve errno during signal handler
- _get_event/_handle_queue: if sigset is given keep blocking
- use ppoll to get uninterrupted from _handle_queue to poll
- secure _add_timer against signals
- _add_timer: fix timer event compare
- _handle_timer: use async safe write(stdout), clock_gettime(gettimeofday)
- _handle_timer: fix missing event remove if current time >= event time
- other files: fix some tkbio.h include issue
2048: Numberwang: add 'rotate the board'
- menu: add 2048 to apps list