Removed unwanted functions and made read/write prototypes consistent in I2C lib
Made I2C functions static to save constructor/instantiation
Major formatting changes to I2C library
Removed unwanted I2C pullup function
Defined constants for I2C timeout error codes
Harmonised/shortened I2C functions parameters
Defined I2C speed and timeout as constants
Changed I2C timeout from milliseconds to microseconds
Added MPU6050, HMC5883L, BMP085 libraries and test sketches
Added a sketch to test different ways to make variables read-only
Removed sketches no longer used