Finish compatibility with the old handlebars:

* foo"bar" is an invalid param
* {{foo}}bar{{/baz}} is invalid
* fix a number of issues with inverse sections
* add partials

lib/handlebars/handlebars_lexer.js

@@ -69,7 +69,12 @@ Handlebars.HandlebarsLexer.prototype.lex = function() {
     // All other cases are IDs or errors
     } else {
       // grab alphanumeric characters
-      while(this.peek().match(/[0-9A-Za-z\.]/)) { this.getchar() }
+      while(this.peek().match(/[_0-9A-Za-z\.]/)) { this.getchar() }
+
+      var peek = this.peek();
+      if(peek !== "}" && peek !== " " && peek !== "/") {
+        return
+      }
 
       // if any characters were grabbed => ID
       if(this.yytext.length) { return "ID" }