Add .mm as an XML extension with heuristic rule
Remove heuristic rules for .mm files
Merge pull request #1706 from pchaigno/mm-xml

Add .mm as an XML extension with heuristic rule
Removing Mercury directory from vendor.yml
Merge pull request #1795 from github/mercury-vendor

Removing Mercury directory from vendor.yml
Add Forth extension .fr; and a sample.
Add 'text' language and heuristics for .fr.
Add .html.fr and .xml.fr; plus samples for .txt.