[sparql mode] Improve parsing of IRI atoms

* Do not treat the opening '<' of an expanded IRI atom as an operator

The existing code would not highlight the IRI atom "<foo#bar>" in the following line as an atom.
FILTER( ?x = "42"^^<foo#bar> )
for example everything after the # would be highlighted as a comment. This is because the sequence "^^<" while all "operator characters", are not all SPARQL operators in this case: the "<" introduces the IRI atom. I special-case the "^^".

* Improve PN_LOCAL parsing to SPARQL 1.1

The following legal sequences of characters from SPARQL 1.1 are additionally parsed as being the right-hand-side of a prefixed IRI.
1) Colons
2) PERCENT escaping
3) PN_LOCAL_ESCAPE escaping

mode/sparql/sparql.js

@@ -60,12 +60,18 @@ CodeMirror.defineMode("sparql", function(config) {
       stream.skipToEnd();
       return "comment";
     }
+    else if (ch === "^") {
+      ch = stream.peek();
+      if (ch === "^") stream.eat("^");
+      else stream.eatWhile(operatorChars);
+      return "operator";
+    }
     else if (operatorChars.test(ch)) {
       stream.eatWhile(operatorChars);
       return "operator";
     }
     else if (ch == ":") {
-      stream.eatWhile(/[\w\d\._\-]/);
+      eatPnLocal(stream);
       return "atom";
     }
     else if (ch == "@") {
@@ -75,7 +81,7 @@ CodeMirror.defineMode("sparql", function(config) {
     else {
       stream.eatWhile(/[_\w\d]/);
       if (stream.eat(":")) {
-        stream.eatWhile(/[\w\d_\-]/);
+        eatPnLocal(stream);
         return "atom";
       }
       var word = stream.current();
@@ -88,6 +94,10 @@ CodeMirror.defineMode("sparql", function(config) {
     }
   }
 
+  function eatPnLocal(stream) {
+    while (stream.match(/([:\w\d._-]|\\[-\\_~.!$&'()*+,;=/?#@%]|%[a-fA-F0-9][a-fA-F0-9])/));
+  }
+
   function tokenLiteral(quote) {
     return function(stream, state) {
       var escaped = false, ch;