Split up Rational numbers into separate values.

This means that FFMSsharp.Rational and LongRational are removed.
This is how it has to be.

Rational numbers can not be properly represented as single values, they
 must be integrated into the equations to work properly.

See: https://github.com/nixxquality/WebMConverter/commit/6bb42571c4810d357b845d5626433d6669898c58