Rename "SEDML" to "SED-ML" in error messages?

[agarny]

Clearly not a major/important issue, but it might be nice to rename SEDML to SED-ML in error messages generated by libCellML?

For example:

An SEDML XML document must not contain undefined elements or attributes in the SEDML namespace. Documents containing unknown elements or attributes placed in the SEDML namespace do not conform to the SEDML specification. Element 'range' is not part of the definition of SEDML Level 1 Version 4.

probably ought to read:

An SED-ML XML document must not contain undefined elements or attributes in the SED-ML namespace. Documents containing unknown elements or attributes placed in the SED-ML namespace do not conform to the SED-ML specification. Element 'range' is not part of the definition of SED-ML Level 1 Version 4.