Colorize DAGs, not models

[ohl]

Don't build the DAG from a colorized model, but colorize the DAG constructed from the uncolorized model. This takes care of two very important issues:

• the maximal number of color flow lines needs not to be known at compile time anymore

• we don't need the huge table of colored vertices anymore to construct the keystones. This should improve performance (dramatically?) and allow to retire the annoying cache files.

All this is possible due to the (trivial) observation that there is never an colored Feynman diagram topology without the presence of the identical uncolored Feynman diagram topology.

[ohl]

This is part of #205 now and can be closed.

[Juergen Reuter]

Milestone v2.0-rc4 deleted