Fix CanonSi handling as well.
Fix CanonSi handling as well.

Canon MakerNotes get validated correctly now. This means that they are
preserved when writing. Awesome.

mono/taglib-sharp,hwahrmann/taglib-sharp,archrival/taglib-sharp,hwahrmann/taglib-sharp,Clancey/taglib-sharp,archrival/taglib-sharp,CamargoR/taglib-sharp,CamargoR/taglib-sharp,punker76/taglib-sharp,Clancey/taglib-sharp,Clancey/taglib-sharp,punker76/taglib-sharp