Added #defines for timeouts as per ISO 11783-3
Changed CAN_FRAME to CAN_Frame; subtle perhaps, but all caps usually
 indicates a #define or other constant
Added uint16_t timeout to CAN_Frame
Added new struct CAN_Filter
Revised keywords.txt to reflect new API
Began standardizing private functions using set and get prefixes and
 camel case
Use const CAN_Frame in write() to minimize memory use
Bugfix for extended ID decoding in CAN_MCP2515::read()
Began revising CAN_K2X.{h,cpp} to match CANClass API