Consistent logging from initiation to launch of Jalview

Jalview launch involves getdown or jalview.bin.Launcher and finally jalview.bin.Jalview. Informationals and debug trace messages are needed for each process to report when jvmmemmax is triggered. Currently these are written to System.err/out in each process, and not reliably captured in a single place.

Work to do:
1. Regularise logging across getdown and jalview.bin.Launcher
2. Provide informational message should report when the maximum memory setting parameter has been used to limit the amount of memory allocated to Jalview by the launcher.
3. Provide debug level log messages to report full details of the memory setting algorithm so people can more easily debug what's going on for their situation.