refactor LogCombiner to use much less memory. closes #402
refactor LogCombiner to use much less memory. closes #402

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