Revert "Minor fix"

This reverts commit cfd9b3e43f4d86ae52e54ab7f3b97650f1c131b9.
Revert "Factorise acceptance function into a module"

This reverts commit 393a4d64c569e7568922fe3f3c75ddc2967fe991.

Conflicts:
	python/ltFit.py
Remove all legacy acceptance functions
Prevent acceptance ratio from going -ve

Add a check against acceptance ratio from going -ve when the
exponential is larger in magnitude than the norm.  Return zero if this
happens.
Demarkers in log file