Chip-io

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* Fixing issue 53 to handle the return values of the set functions in pwm_enable.
* Start of whole library debug for 55

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* Fixing issue 50 where I broke GPIO.cleanup() and SOFTPWM.cleanup() when no input is specified.

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* Added setmode() function for GPIO to maintain compatibility with Raspberry Pi scripts, this function literally does nothing
* Added per pin cleanup functionality for GPIO and SoftPWM so you can unexport a pin without unexporting every pin
* Updated README to make edge detection wording a little better and to add the per pin cleanup code
* Version update since I blasted through 3 issues on github and feel like we need a nice bump to 0.3

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* Fix to the Enable 1.8V Pin code as it wasn't working due to bit shifting isn't allowed on a float.
* Updated README to denote the PocketCHIP Pin names better

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* Fix to keep the GPIO value file open until the pin is unexported (issue 34)

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* Updates to the pytest code for HWPWM and SoftPWM
* Removed the i2c-1 load/unload support in OverlayManager as CHIP Kernel 4.4.13 has that bus brought back by default