as11 metadict: change 3D to ThreeD to make it XML compliant
as11 metadict: change 3D to ThreeD to make it XML compliant

XML element names cannot start with a digit
ThreeD is what is also used in AS11 DPP XML, mxf2raw and bmxtranswrap.

kierank/bmxlib-bmx,Limecraft/ebu-bmx,stuarthicks/bmx,stuarthicks/bmx,xunchangguo/BMX,Limecraft/ebu-bmx,xunchangguo/BMX,ebu/ebu-bmx,ebu/ebu-bmx,Limecraft/ebu-bmx,xunchangguo/BMX,ebu/ebu-bmx,kierank/bmxlib-bmx,stuarthicks/bmx,kierank/bmxlib-bmx