Restructured MCMC chain debugging code.  Issue #566.
Restructured MCMC chain debugging code.  Issue #566.

Changed the mechanism for including this code from
uncommenting various lines to altering the value of
a single boolean field.

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