* draco: update versions
+ Added versions 7.3.0 and 7.4.0.
+ Change several variants to be default TRUE since most consumers need these
variants enabled (eospac, lapack, parmetis, superlu-dist). Change variant name
for `+superlu_dist` to use hyphen instead of underscore. This makes the
variant name consistent with the spackage name for `superlu-dist`.
+ Clean up `depends_on` instructions and avoid specifying `type` when possible.
+ Provide patch files that are necessary for some machines (mostly Cray
machines).
* Remove trailing whitespace.
* Revert variant name to use underscore.
* add maintainer information.
