Mother of all 7603 XDF files

[NSFW]

I've done 3 things here:

1) Moved the ETC-related parameters out of the idle section and into a new "Electronic Throttle Control" section under the Engine Calibration section.
2) Added two PTO parameters to a new "Power Take-Off" section.
3) Replaced the checksum stuff with what was in DzidaV8's XDF, because it uses built-in Tuner Pro checksum code rather than a DLL.

The data in table B6614, "Max Torque By RPM Vs Fuel E%" looks to me like the XDF should have two more rows in each E% column, but I haven't figured out how to fix that.