Trace log sort

Sort items to be logged, one of none, alphabetic, smart.

• none = no sorting at all. Items appear in order they appear in the XML.
• alphabetic = sort items alphabetically.
• smart = Group loggers with same id-prefix, where the prefix of an id is defined as the part of an id before the first full stop. This way, multi-partition analysis generated by BEAUti get all related log items together in Tracer.