Add support for filenames ending in .txt

Author: Blake Gearin

README.md

@@ -17,6 +17,9 @@ The following filename extensions are supported:
   - `.ps`
   - `.pulp`
   - `.pulpscript`
+  - `.ps.txt`
+  - `.pulp.txt`
+  - `.pulpscript.txt`
 
 ## Links
 

package.json

@@ -31,7 +31,10 @@
         "extensions": [
           ".ps",
           ".pulp",
-          ".pulpscript"
+          ".pulpscript",
+          ".ps.txt",
+          ".pulp.txt",
+          ".pulpscript.txt"
         ],
         "configuration": "./language-configuration.json"
       }