Revision history for RPi-Const

1.04    2018-06-05
        - added constants for MCP23017 GPIO expander register locations
          (mcp23017_registers tag) for upcoming RPi::GPIOExpander::MCP23017
          release

1.03    2018-05-29
        - added pwm_defaults tag, constants for default PWM settings
          (closes #2)

1.02    2017-07-13
        - re-released RPi::WiringPi::Constant as RPi::Const

1.01    2017-07-08
        - added new tag :pwm_mode that contains the values for setting the PWM
          mode to either MS (mark-space) or BAL (balanced) mode

1.00    2017-06-24
        - added new tag :altmode that contains the value for the Pi pin ALT
          modes

0.02    unknown
        - added edge detection constants
        - added PUD constants
        - added setup mode constants

0.01    unknown
        - first version, released on an unsuspecting world.