adds support for browserify

this pr also changes some code to make compatible with the browser. It exposes the global variable "carto"
One of the problems is mapnik reference, the module is not read to work with browserify since it loads modules dynamically. It does not make sense to make it compatible since mapnik-reference is not going to be used so people must to set the reference needed before parse/render:

carto.tree.Reference.setData(reference)

Makefile

@@ -3,6 +3,11 @@
 #
 
 expresso = ./node_modules/.bin/mocha
+BROWSERIFY = ./node_modules/.bin/browserify
+TREE_FILES = $(shell ls ./lib/carto/tree/*.js)
+
+# generates the requirement options for browserify for modules loaded dinamically (see, lib/carto/index.js)
+BROWSERIFY_REQUIRES = $(foreach var,$(TREE_FILES), -r $(var):$(subst .js,,$(subst ./lib/carto,.,$(var))))
 
 lint:
 	./node_modules/.bin/jshint lib/carto/*.js lib/carto/tree/*.js
@@ -17,4 +22,10 @@ endif
 
 check: test
 
+dist:
+	mkdir -p dist
+
+dist/carto.uncompressed.js: dist $(shell $(BROWSERIFY) --list lib/carto/index.js) $(TREE_FILES)
+	$(BROWSERIFY) --require $(BROWSERIFY_REQUIRES)  --debug lib/carto/index.js --standalone carto > $@
+
 .PHONY: test

lib/carto/index.js

@@ -4,7 +4,9 @@ var util = require('util'),
 
 
 function getVersion() {
-    if (parseInt(process.version.split('.')[1], 10) > 4) {
+    if (typeof(this['window']) !== undefined) {
+        return require('../../package.json').version.split('.');
+    } else if (parseInt(process.version.split('.')[1], 10) > 4) {
         return require('../../package.json').version.split('.');
     } else {
         // older node

lib/carto/tree/reference.js

@@ -5,7 +5,6 @@
 (function(tree) {
 
 var _ = require('underscore'),
-    mapnik_reference = require('mapnik-reference'),
     ref = {};
 
 ref.setData = function(data) {
@@ -24,6 +23,7 @@ ref.setData = function(data) {
 };
 
 ref.setVersion = function(version) {
+    var mapnik_reference = require('mapnik-reference');
     if (mapnik_reference.version.hasOwnProperty(version)) {
         ref.setData(mapnik_reference.version[version]);
         return true;

package.json

@@ -46,7 +46,8 @@
     "jshint": "0.2.x",
     "sax": "0.1.x",
     "istanbul": "~0.2.14",
-    "coveralls": "~2.10.1"
+    "coveralls": "~2.10.1",
+    "browserify": "~7.0.0"
   },
   "scripts": {
     "pretest": "npm install",