[EMF] Little improve of freehep-graphicsio-emf for font quality and image ratio.

Hello,

I change the Font quality from ANTIALIASED_QUALITY (4) to CLEARTYPE_QUALITY (5), because it's look much better in word and windows standard emf viewer.

In org.freehep.graphicsio.emf.EMFHeader, I passed the static field screenMM public because by default the dimension are from a 4/3 screen and with another one (mine is 16/9) the ratio is not keeped.

Thanks.