Update Simplified Chinese help translation.
[l10n] Updated German translation
Work on the Firebird provider, thanks to Faghmie Davids

2 providers are created: one for the client version and one
for the embedded server version
GdaConfig: sort providers by ID
Firebird provider: fixed compilation dependencies
Correction for bug #665917
[l10n] Updated German translation
Updated Czech translation
Allow the two kinds of Firebird providers to be used at the same time
Added missing files to POTFILES.in
Another correction for bug #665917
Updated Czech translation
Merge branch 'libgda-vala'
[l10n] Updated German translation
Enable correct detection of Vala
Updated Spanish translation
Updated Slovenian translation
GdaData.Object.table API change: changed to read-only attribute.

* GdaData.Object.table must be overrided by derived classes maybe using an static string or any other method.
Fix libgdadata installation issues. Simplifing example for GdaData.Object.
Work in progress: Fixing GdaData.DataModelIterable implementing Gda.DataModel
interface. Missing some functions not correctly implemented.