fix(showdown): fix for options merging into globalOptions

Passing an option to a specific converter affects other instances of the converter since options are merged into showdown's global options.
This commit fixes that.

Closes #153

dist/showdown.js

@@ -1,4 +1,4 @@
-;/*! showdown 15-05-2015 */
+;/*! showdown 26-05-2015 */
 (function(){
 /**
  * Created by Tivie on 06-01-2015.
@@ -133,7 +133,7 @@ showdown.Converter = function (converterOptions) {
 
   converterOptions = converterOptions || {};
 
-  var options = globalOptions,
+  var options = {},
       langExtensions = [],
       outputModifiers = [],
       parserOrder = [
@@ -144,6 +144,12 @@ showdown.Converter = function (converterOptions) {
         'unescapeSpecialChars'
       ];
 
+  for (var gOpt in globalOptions) {
+    if (globalOptions.hasOwnProperty(gOpt)) {
+      options[gOpt] = globalOptions[gOpt];
+    }
+  }
+
   // Merge options
   if (typeof converterOptions === 'object') {
     for (var opt in converterOptions) {

src/showdown.js

@@ -131,7 +131,7 @@ showdown.Converter = function (converterOptions) {
 
   converterOptions = converterOptions || {};
 
-  var options = globalOptions,
+  var options = {},
       langExtensions = [],
       outputModifiers = [],
       parserOrder = [
@@ -142,6 +142,12 @@ showdown.Converter = function (converterOptions) {
         'unescapeSpecialChars'
       ];
 
+  for (var gOpt in globalOptions) {
+    if (globalOptions.hasOwnProperty(gOpt)) {
+      options[gOpt] = globalOptions[gOpt];
+    }
+  }
+
   // Merge options
   if (typeof converterOptions === 'object') {
     for (var opt in converterOptions) {