Fixes for jOpenDocument compatibility.

Merge pull request #5 from mmulqueen/jopendocument_fix

jOpenDocument fix

Gnumeric support and more.

0.3.0

Improved compatibility with Gnumeric and testing for Gnumeric via ssc…

Multiple sheet support

Merge pull request #1 from mmulqueen/sheets

Can now write to multiple sheets rather than just one.