Add syntax highlighting for the Clean language

.gitmodules

@@ -737,3 +737,6 @@
 [submodule "vendor/grammars/Elm"]
 	path = vendor/grammars/Elm
 	url = https://github.com/elm-community/Elm.tmLanguage
+[submodule "vendor/grammars/atom-language-clean"]
+	path = vendor/grammars/atom-language-clean
+	url = https://github.com/timjs/atom-language-clean.git

grammars.yml

@@ -176,6 +176,8 @@ vendor/grammars/atom-fsharp/:
 - source.fsharp.fsi
 - source.fsharp.fsl
 - source.fsharp.fsx
+vendor/grammars/atom-language-clean:
+- source.clean
 vendor/grammars/atom-language-purescript/:
 - source.purescript
 vendor/grammars/atom-language-stan/:

lib/linguist/languages.yml

@@ -571,7 +571,7 @@ Clean:
   extensions:
   - .icl
   - .dcl
-  tm_scope: none
+  tm_scope: source.clean
   ace_mode: text
 
 Click:

vendor/licenses/grammar/atom-language-clean.txt

@@ -0,0 +1,25 @@
+---
+type: grammar
+name: atom-language-clean
+license: mit
+---
+Copyright (c) 2015 <Your name here>
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.