Values not escaped when using <node>.OutputXML(true)

[highway900]

When XML with escaped characters such as < is loaded it will be transformed into its un-escaped version. Then when OutputXML(true) is used the inner text values are returned in the un-escaped version.
This PR will add escaping to the inner text of nodes for the output of OutputXML(true)

[coveralls]

Coverage increased (+0.3%) to 71.262% when pulling 9b34027 on highway900:master into 23c951a on antchfx:master.

[zhengchun]

@highway900 ,I'm sorry, looks i'm made a mistake. I'm merged you PR and push to github but your name not listed in the main contribution page, so i'm undo my last push and push again still not successful.

I'm googling , looks your email in the git config and github account is not same cause this issue。you can trying add your new git config email to github email list or re-open new PR.

Thanks again.