Syntax support for block (triple-quoted) strings

Closes #14

Author: jparise

syntax/graphql.vim

@@ -17,6 +17,7 @@ syn keyword graphqlBoolean  true false
 syn keyword graphqlNull     null
 syn match   graphqlNumber   "-\=\<\%(0\|[1-9]\d*\)\%(\.\d\+\)\=\%([eE][-+]\=\d\+\)\=\>"
 syn region  graphqlString	start=+"+  skip=+\\\\\|\\"+  end=+"\|$+
+syn region  graphqlString   start=+"""+ end=+"""+
 
 syn keyword graphqlKeyword on nextgroup=graphqlType skipwhite
 

test/syntax.vader

@@ -39,10 +39,13 @@ Execute (Boolean assertions):
 Given graphql (Strings):
   ""
   "Hello World"
+  """Triple-quoted
+  string"""
 
 Execute (String assertions):
   AssertEqual 'graphqlString', SyntaxOf('""')
   AssertEqual 'graphqlString', SyntaxOf('"Hello World"')
+  AssertEqual 'graphqlString', SyntaxOf('"""Triple-quoted\nstring"""')
 
 # https://facebook.github.io/graphql/#sec-Type-Conditions
 Given graphql (Type Conditions):