Add stylus support

lib/linguist/language.rb

@@ -32,7 +32,7 @@ module Linguist
     #
     # Returns an array
     def self.detectable_markup
-      ["CSS", "Less", "Sass", "TeX"]
+      ["CSS", "Less", "Sass", "Stylus", "TeX"]
     end
 
     # Detect languages by a specific type

lib/linguist/languages.yml

@@ -1519,6 +1519,11 @@ Standard ML:
   - sml
   primary_extension: .sml
 
+Stylus:
+  type: markup
+  group: CSS
+  primary_extension: .styl
+
 SuperCollider:
   type: programming
   color: "#46390b"

lib/linguist/samples.json

@@ -363,6 +363,9 @@
       ".sig",
       ".sml"
     ],
+    "Stylus": [
+      ".styl"
+    ],
     "SuperCollider": [
       ".sc",
       ".scd"