Add Tcl module extension

Tcl uses modules which have the extension .tm, so I have added this
extension for Tcl.
Fix languages.yml 'interpreters' key documentation
Merge branch 'master' into 891
Adding .tm Tcl samples
Merge branch 'master' into 891-update

Conflicts:
	lib/linguist/samples.json
Merge pull request #1041 from Mikulas/typo

Fix languages.yml 'interpreters' key documentation
Merge pull request #1084 from github/891-update

891 update