Deprecate wait() in favour of acquire(), try_acquire(),
try_acquire_for() and try_acquire_until().
Brings Semaphore more into line with CMSIS-RTOS 2 (which uses "acquire"),
itself (as it has "release"), and other classes having "try", "try for"
and "try until".
Also steps away from vague "wait" term - the primary operation here is
to acquire the semaphore, and this will of course sleep.
Add the classes Task, TaskBase and TaskQueue. TaskQueue queue is an
interface class which can be implemented by anything which can run
code. Task and TaskBase are concrete classes which allow callbacks
to be posted to a TaskQueue to be run.