lalapps_MakeSFTDAG improvements
Two changes to take care of https://git.ligo.org/CW/lalsuite/issues/36 and https://git.ligo.org/CW/lalsuite/issues/39:
MakeSFTDAG: new options --datafind-path and --makesfts-path to override env variables or system defaults
-hierarchy: first try user option, then env variables, then system default
lalapps_MakeSFTDAG: new option --request-memory
-for actual MakeSFTs step only, gw_data_find will probably never be memory-critical
@evan-goetz @keith-riles @gregory.mendell you might want to have a look. If you have the env variables set and don't issue the new user options, it should behave as before.
Note I wasn't able to find any unused reasonably mnemonic short options, so -j -J and -Y for no better reason than that those letters were still available. Also if I ever get too bored, I might consider porting this to argparse, since the current getopt usage is really tedious...
I got a failing pipeline at the moment, but it might just be due to the way I've force-pushed to the branch repeatedly. Will investigate again later.