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 293b9d07

There might be some lingering old uses of "xyzcontrol"
instead of "xyzparam", but whatever.

cmHandler ready for cmToStr() and strToCm() functions

- 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

Hopefully there are no copy-paste bugs

- added some comments in commands.c/h about usage of the file
- added a MAX_CONTROLLER_ID and MAX_CONTROL_VAL_ID to the enums in commands.h
- implemented cb_set_control in callbacks.c to work with the new parameter struct
- changes the parameter_struct to now contain an array of pid_controllers instead of a bunch of random PID_t members
- the new parameter_struct array can now be accessed by controller ID as defined in commands.h

Prepared for parsing the new data formats. Data isn't formatted
or parsed yet, though.

No more memory leaks! Unfortunately each memory leak was replaced
by a potential buffer overflow. Basically, the code was riddled
with functions that accept a char ** data, which
is malloced and then formatted. This was then leaked.
Now, it accepts a char * data, which is allocated on the stack
by the calling function. However, there is no bounds checking,
because that is slightly more involved.

See todos in format_command and parse_packet.

added the datatype parameter back into MessageType struct in commands.h because Jake actually does need it.