Changelog

• HardwareSPI needs to be a abstract base class (#127)
• Bugfix: Small buffer size causes buffer overrun when invoking String::Ctor with large float/double value. (#131)
• Changing return type of requestFrom from uint8_t to size_t allows the function to return the correct amount of bytes read (since internally it's already a size_t which is downcast to a uint8_t upon returning it. (#132)