LinGui: build preset import/export tables from hb_encoder_t tables

This makes tracking additions to libhb encoders completely transparent to
the LinGui. Changes or deletions still require special handling to ensure
backwards compatibility.


git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@5140 b64f7644-9d1e-0410-96f1-a4d463321fa5