Added ability to get/set PID constants. Passes regression tests, and is backwards-compatible. Does not support setpoints, because they will be set via a different interface

Revert "Revert "Merge branch 'master' of git.ece.iastate.edu:danc/MicroCART_17-18 into batch-setpid""

This reverts commit b9292f1c.

Yes, this is a revert-revert. Brendan broke all the things.

This reverts commit bcd4f7e7.

Yes, this is a revert-revert. We should suspend Brendan's git license pending
completion of a remedial course and 20 hours community service.

This reverts commit 6d4c0a2e

This reverts commit 293b9d07

Resets recursively, keeping track of children. Created tests, which pass. Computation terminates on graph cycles. Added comments.

Some refactoring, separating node type from node instance. Added parameters, and disabled ability to set inputs.

Modified test script and fixed setParam function

see cb_setparam, cb_getparam

- Realised that controller value may get confused with the actual value of the PID terms in the controller. To avoid this confusion in the future I have refactored things referencing the PID constant to now be called "control_parameter"
- There are quite a few instances of variables that changed.
- Sorry Jake

I was not copying the float value into the array correctly.
Hopefully I have it right now... will check with eric when he gets back from making tea.

- the desired format is in the comment above the funciton
- format should be controller ID, controller value ID, controller value
- should now be sending the data in the correct format

changed getcontrol to respond with the same message ID that was received from groundstation in the original getcontrol command