Enabling "Toggle Full Namespace" generates invalid XML IDs in the SCXML editor

The SCXML editor uses two colons :: as a namespace delimiter, but the colon is not a valid character in XML IDs. This causes the qscxml compiler to fail to compile the state chart. I think a period should be used instead of the double colon.

To reproduce (assuming SCXML editor is already enabled):

1. Create a new Qt Widgets project.
2. Add a new SCXML state chart.
3. Add "QT += scxml" to the .pro file.
4. Within the state chart editor, create an empty state.
5. Add another empty state within that state.
6. Compiling the application at this point should work fine.
7. But now, enable the "Toggle Full Namespace" option.
8. Upon attempting to recompile, you will get errors like:

error: 'State_1::State_2' is not a valid XML ID