Make HEX a function instead of a macro.
Remove unused macro
Move stuff from task.h to kernel_supplement.h
Rename 'rbc_period' to 'tick_period'
Rename some Task APIs from "rcb" to "ticks".
Rename Flags::max_rbc to Flags::max_ticks.
Rename 'check_rbc'.
Rename some stuff in replayer.cc from 'rcb' to 'ticks'
Rename more stuff in replayer.cc from rcb to ticks
Rename even more stuff in replayer.cc from rcb to ticks
Rename more replayer stuff from rcb to ticks
Rename some stuff from rbc to ticks.
Rename more stuff from rbc to ticks.
Rename more stuff from rbc to ticks
Rename 'rbc' stuff to rcb or ticks.

From now on, 'rcb' should only be used when we're referring specifically
to retired conditional branches; when we're referring to general
progress-measuring we should just say 'ticks'. 'rbc' should never
be used for anything.