Merge branch 'feature/list-where' of git://github.com/zeckalpha/wren into zeckalpha-feature/list-where

Conflicts:
	builtin/core.wren
	src/wren_core.c

src/wren_core.c

@@ -67,6 +67,14 @@ static const char* libSource =
 "    }\n"
 "    return result\n"
 "  }\n"
+"  \n"
+"  where (f) {\n"
+"    var result = []\n"
+"    for (element in this) {\n"
+"      if (f.call(element)) result.add(element)\n"
+"    }\n"
+"    return result\n"
+"  }\n"
 "}\n";
 
 // Validates that the given argument in [args] is a Num. Returns true if it is.
@@ -275,9 +283,9 @@ static PrimitiveResult callFunction(WrenVM* vm, Value* args, int numArgs)
   {
     fn = AS_FN(args[0]);
   }
-  
+
   if (numArgs < fn->numParams) RETURN_ERROR("Function expects more arguments.");
-  
+
   return PRIM_CALL;
 }