Basic I2C functionality support

[rexut]

Is your feature request related to a problem? Please describe.
Currently the VeryLittleWire library does nothing.

Describe the solution you'd like

• Porting foollowing methods from Python 2 to Python 3:
  • littleWire::device::i2c_init() as i2cInit() (note the CamelCase syntax)
  • littleWire::device::i2c_beginTransmission() as i2cBeginTransmission() (note the CamelCase syntax)
  • littleWire::device::i2c_send() as i2cSend() (note the CamelCase syntax)
  • littleWire::device::i2c_endTransmission() as i2cEndTransmission() (note the CamelCase syntax)
  • littleWire::device::i2c_requestFrom() as i2cRequestFrom() (note the CamelCase syntax)
• Check the new C/C++ interface and sync – seems to be complete new witch firmware 1.x.
  • littleWire.c::i2c_init() as i2cInit() (note the CamelCase syntax)
  • littleWire.c::i2c_start() as i2cStart() (note the CamelCase syntax)
  • littleWire.c::i2c_write() as i2cWrite() (note the CamelCase syntax)
  • littleWire.c::i2c_read() as i2cRead() (note the CamelCase syntax)
  • littleWire.c::i2c_updateDelay() as i2cUpdateDelay() (note the CamelCase syntax)
• Protect the integration with unit tests.
• Ensure API documentation is there.

Additional context

• Provide an example or CLI tool. Be inspired by the original C implementation: https://github.com/littlewire/Little-Wire/tree/master/software/examples

Intended overall functions:

• 4 channel GPIO.
• 2 channel ADC with 10 bit resolution.
• 2 parallel hardware PWM outputs.
• SPI interface.
• I2C interface.
• 1-Wire interface.
• WS2812 RGB LED interface.
• Multiple device support. CURRENTLY NOT (YET) POSSIBLE

Expected pin mapping:

Pin	USBtinyISP	Hard-PWM	Soft-PWM	ADC	I2C	SPI	1-Wire	WS2812	CDC-232
1	MISO	CH_B	CH_2	-	-	DO	-	DATA	TX
2	SCK	-	CH_3	CH_1	SCL	SCK	DATA	DATA	RX
3	RESET	-	-	CH_0	-	CS	-	DATA	-
4	MOSI	CH_A	CH_1	-	SDA	DI	-	DATA	-

^{_{https://littlewire.github.io/}}