Fix incorrect escaping of characters '9', 'z' and 'Z'

When escaping attributes like 'ZipCode' the escaped value is '_ipCode'; same for '91' -> '_1' and 'zip' -> '_ip'

The reason is that the loop for filling the escape map runs to < instead of <=.
Merge pull request #28 from TheMadButcher/patch-1

Fix incorrect escaping of characters '9', 'z' and 'Z'