High Speed Data Transfers/Optimization

Changes:

- Enable PTX at radio begin, in standby-I mode
- Enable PTX at radio stopListening(); in standy-I mode

- Radio startListening
- removed delay. What is there to wait for when the radio will just be
listening anyway?

- Radio powerUp
- radio will need to be powered up after configuration
- radio will not power down unless instructed to
- need to issue radio.txStandBy(); when finished transmitting to engage
standby-I mode

- Added txStandBy() to drop to standBy-I mode if not switching to RX
mode

- Radio Write: Sped up
- radio previously did not use standby mode effectively, after TX
sending of each packet, the radio is
powered down introducing a 1.5ms delay in addition to the 130us delay
from standby.
- No observe-tx code, a simple NOP cmd is sent to get the status info
- No millis() timeout, hanging condition should only occur because of
faulty code
- Simplified whatHappened() code
- Flush TX FIFO if MAX_RT met as lib does not support re-transmit
instead of flush every time.
- Remove ack size monitoring
- No powerdown needed,

- Added writeClear() function for writes that need the interrupt flags
cleared (ack payloads, etc). Same as write() otherwise

- Radio startWrite: Sped up
- Enable PTX mode is now done in stopListening() code. Enter TX mode by
writing CE high.
This brings the data transfer capabilities up to a reasonable level
- No need to power up, already in Standby-I mode
- No need for delayMicroseconds() in write functon.
- No need for delay after writing CE high
- Does not enter Standby-I mode be default. It is up to the MCU to call
the new txStandBy() function to enter standby-I mode from PTX if not
switching back to PRX

- Radio available:
- Now checks the FIFO buffer instead of the interrupt flag (no missed
data)
- Moved clearing of interrupt flags to Read()

- Radio read:
- No longer returns any value - use available to check for more data

- Radio isAckPayloadAvailable() now checks the FIFO directly

- Radio getDynamicPayloadSize() - Per the datasheet, added fix to flush
corrupted packets