Adding support for Hoplon files

See https://github.com/tailrecursion/hoplon-demos/blob/master/todoFRP/src/index.cljs.hl for an example and https://github.com/tailrecursion/hoplon for the full project.
.mask support for Mask
Merge pull request #938 from tenbits/master

Add Mask markup language
Merge pull request #854 from cndreisbach/patch-1

Adding support for Hoplon files