Move _devel to stable and add inlist_to_mesascript.

More or less stable now. inlist_to_mesascript allows the translation of
normal MESA inlists into a ready-to-go basic mesascript file. Added much
more documentation to the comments.
Add the inlist2mesascript command-line utility.

If ruby can find mesa_script.rb, this command line utility takes two arguments,
a source inlist file and a destination filename, and converts the source inlist
to a mesascript file that should generate the original inlist back (albeit
commentless and reformatted).