Fix compilation (missing file)
Re-enable other controllers now the theories are fixed
polyc: change to the directory containing the file to be compiled

This way, where you run polyc from doesn't matter.
Make quanto-xml-to-json work again

We no longer have any way of producing XML output.  quanto-core cannot
read XML input either; instead, you need to use quanto-xml-to-json to
convert old graphs and rulesets.

quanto-xml-to-json should work for all existing theories.  There is
(obviously) no need to add new theories to this tool.

Also introduces File_Io as a replacement for the old Reader and Writer
structures.
Remove old never-completed XML-protocol stuff
Remove file from rtechn test dir that isn't even for that theory
Convert XML files to JSON format
Fix isaplanner_rtechn JSON graph parsing
Update example code and regression tests to use JSON files

Even managed to get the old red-green ruleset rewriter tests working
(not that they pass - there's something up with matching).
Use the File_Io structure where sensible