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- MRAA support originally by @prophet-roshak #74
- Updated to migrate support files completely into arch/MRAA and
minimize changes to the source files
- Changes as per suggestions from @arfoll

- incorrect define prevents dual devices from sharing the SPI BUS

- Update littlewire makefile by @lnxbil for new hardware support
template

- Update main Makefile (CCFLAGS)
- Update examples_RPi Makefile (CCFLAGS)
- Update examples_RPi/gettingstarted.cpp with BBB/spidev pins example

https://github.com/TMRh20/RF24/commit/e2abd640a296e1be9b2abc0d27bbd5caa1affa78#commitcomment-9750201

Move to new template for:
- RPi (BCM2835)
- BBB (SPI_DEV)
- LittleWire

RPi can be forced to use SPIDEV by calling "sudo make install
RF24_SPIDEV=1"

Potential RPi 2 support via updated bcm2835.c (version 1.39)

- Created the appropriate files for Due and ATTiny under arch/Due and
arch/ATTiny
- Modify RF24_config.h to suit the new changes
- Modify detection for Arduino Due ( ARDUINO_SAM_DUE )
- Update RF24.cpp for cleaner Due detection

Due changes are tested and working
ATTiny changes compile but are untested

From https://github.com/mlsorensen/RF24

Conflicts:
	RF24.cpp

Merge master with updates branch

Some changes to get different revisions of NRF24L01+ modules working. by @dsbaha 

- remove additional toggle_features as already enabled in radio start

Address fix for attiny example sketch

The addresses are reversed when using with the GettingStarted sketch as
described in the comments. This causes the arduino and the tiny to both
be in receiver mode.

adapted python wrapper for RF24 interface changes in txStandBy and startFastWrite by @mz-fuzzy re #64 

Conflicts:
	RPi/pyRF24/pyRF24.cpp

- Add optional values for startFastWrite and txTimeout
#64

- Add optional startTx to startFastWrite() function:
a: Allows software to fully utilize FIFO buffers for buffering payloads
to the TX FIFO, while remaining in RX mode, instead of storing data in
RAM etc.
b: Default is still to start sending immediately unless startTx is
included and set to 0

Note: This will not work correctly if using ack-payloads. Tx FIFO is
flushed when switching between RX/TX modes to prevent data corruption.

- Added optional startTx to txStandBy(timeout,startTx)
a: Allows automated sending of buffered data, with indication of success
or failure for the bulk data transfer.
b: Default is still to not initiate sending, and not leave RX mode.
c: Calling this with startTx set to true will automatically call
radio.stopListening() to begin transmission.

Example:
radio.startFastWrite( &time, sizeof(unsigned long), false );
radio.startFastWrite( &time, sizeof(unsigned long), false );

if (!radio.txStandBy(100, true) ){  printf("failed.\n\r");  }
radio.startListening()

Using the handy hardware/firmware combination LittleWire by Ihsan
Kehribar, you can access the SPI bus on every libusb-capable machine.
This approach is far from fast, but it works for sending or receiving
simple commands.

For further information about LittleWire, please see the corresponding
homepage at http://littlewire.cc/

- Potential patch for issues setting 'extra features' (Dyn Ack, Ack Pld,
Dyn PL)
- Testing the effect of leaving the features register permanently
enabled, and resetting to 0 on reset/restart
- Remove stray csn(LOW)

- RPi/Linux - Configure SPI BUS sooner before each interaction
- RPi/Linux - Add slight delay after setting SPI config
- ALL - Remove delay from startListening()
- ALL - Define per-datarate delays as per results of extensive testing
- Increase hardware fail timeout
- Remove lastAvailableCheck and listeningStarted variables
- Remove delay during call to available()
- Add txRxDelay variable, set when the datarate is configured

- Added more detailed setup information
- Clarified the user config portion of the example python sketch per #49

- Enable warnings by default on linux if the radio is not responding
- Revert reduction in SPI speed pending further testing

- Updated gettingStarted examples to demonstrate proper pipe/address
handling by assigning a unique id to each node
- Updated gettingstarted_call_response to demonstrate 'proper' use of
ack payloads
- Added gettingstarted_handling_data example
- Added pingpair_irq_simple to demonstrate bidirectional communication
via interrupts
- Updated standard pingpair_irq example
- Use Serial.println(F()); instead of printf

Adding SPI enum to RPi python wrapper per #49