CDATA handling

[MaxSagebaum]

I posted this already in the imatrix gsl repo but got no answer. It is basically a first crude patch for CDATA handling. Here the original post:
(imatix#98)

I have the same problem and written up a crude patch as an example how it could be implemented.

If such an addition would be welcome I could then modify the patch in order to add more checks make it more robust etc.. If yes, I would appreciate some comments on how the same functionality can be archived with more functionality that is already available in gsl.

https://gist.github.com/MaxSagebaum/2c2e3443ca36e093e65025692bfc1220#file-0001-hanlding-of-cdata-as-one-single-value-item-patch