* rmt driver initial version

* supporting conti mode plus interrupts

* using conitnous mode for sending more data

* working continous mode

* rmt driver cleanup after conti mode

* initial version of rmt driver

* adding a simple example

* adding channel and block locks

* modified of rmt interface for simpler/easier usage

* adding header sentinels, split interface to common and additional settings

* Fixes per code review + support for rx callback mode

* renamed internal structures and enums, fixed formatting

* cmake support for rmt

* refactored tx-conti interrupts to function to make it more readable

* added Tx and Rx examples

* added license headers

* minor updates per review

* used struct access, renamed defines, corrected diagram