Merge pull request #98 from btd/less_locals

Add context helpers to less engine.

lib/mincer/engines/less_engine.js

@@ -156,12 +156,21 @@ function lessImporterSync(file, currentFileInfo, callback, env) {
 }
 
 // Render data
-LessEngine.prototype.evaluate = function (context/*, locals*/) {
+LessEngine.prototype.evaluate = function (context, locals) {
   var self   = this;
 
   var error  = null,
       result = null;
 
+  var fixedLocals = {};
+  Object.keys(locals).forEach(function(local) {
+    fixedLocals[local] = function(lessArg) {
+      return new less.tree.Anonymous(locals[local](lessArg.value));
+    };
+  });
+
+  _.extend(less.tree.functions, fixedLocals);
+
   var parser = new (less.Parser)({
     paths:          [path.dirname(this.file)].concat(context.environment.paths),
     optimization:   1,