Add generic parameter keywords to Kotlin lexer (#1504)

Kotlin allows three keywords to be used inside a list of generic
parameters: `in`, `out` and `reified`. In addition, it supports the use
of `:`. This commit adds support for these elements to the Kotlin lexer.

lib/rouge/lexers/kotlin.rb

@@ -105,7 +105,8 @@ class Kotlin < RegexLexer
       state :generic_parameters do
         rule class_name, Name::Class
         rule %r'(<)', Punctuation, :generic_parameters
-        rule %r'(,)', Punctuation
+        rule %r'(reified|out|in)', Keyword
+        rule %r'([,:])', Punctuation
         rule %r'(\s+)', Text
         rule %r'(>)', Punctuation, :pop!
       end

spec/lexers/kotlin_spec.rb

@@ -31,5 +31,11 @@
     it 'recognizes label reference in break statement' do
       assert_tokens_equal 'break@label', ["Keyword", "break"], ["Name.Decorator", "@label"]
     end
+
+    it 'recognizes type modifiers' do
+      for modifer in ['reified', 'out', 'in'] do
+        assert_tokens_equal "<#{modifer} T>", ["Punctuation", "<"], ["Keyword", modifer], ["Text", " "], ["Name.Class", "T"], ["Punctuation", ">"]
+      end
+    end
   end
 end

spec/visual/samples/kotlin

@@ -162,10 +162,14 @@ fun `String`.`backTickedExtensionFunction`() {
    return
 }
 
-fun <T, V> String.genericExtensionFunction() {
+fun <T, V : Comparable> String.genericExtensionFunction() {
    return
 }
 
+inline fun <reified T> membersOf() = T::class.members
+public interface List<out E> : Collection<E> {}
+public interface Comparable<in T> {}
+
 @Deprecated("This is an annotation")
 fun anAnnotatedFunction() = {
 }