mutex_t and mutex_ are reverted to non recursive versions (pre SDK1.2.0) and new recursive_mutex_t and recursive_mutex_ functions have been added
PICO_MUTEX_ENABLE_SDK120_COMPATIBILITY flag has been added to allow old SDK1.2.0 compatibility (i.e. mutex_t can be used recursively or not) but this is slower (and is will be removed in a future version)
- Add recursive_mutex
- Make all locking primitives and sleep use common overridable wait/notify support to allow RTOS
implementations to replace WFE/SEV with something more appropriate
- Add busy_wait_ms