keep trees linked when splitting on codon partitions in BEAUt. fixes #415
keep trees linked when splitting on codon partitions in BEAUt. fixes #415

Anaphory/beast2,CompEvol/beast2,tgvaughan/beast2,CompEvol/beast2,Anaphory/beast2,CompEvol/beast2,Anaphory/beast2,CompEvol/beast2,Anaphory/beast2,tgvaughan/beast2,tgvaughan/beast2,tgvaughan/beast2