reformat the export .m files

note that some jointChoiceProb seems to be overflow
the duration of a feasible decision is in 1..DH
if there is only one decision for a state, compute EV & EW directly

otherwise there exist significant round errors
bugfix: change to the value of the subsequent state
reformat .m data file and output more debug data

the exported files are renamed to *.txt to make ST2
display the plain text, otherwise slow to open in ST2
due to the code highlight