Sort configuration map alphabetically when exporting

[mfg92]

Problem
Currently, the order of key-value pairs in the exported configuration map (XML) is not deterministic. This makes it difficult to compare differences between two exported configuration maps.

Solution
I propose to sort the configuration map alphabetically by key during export.

Background
We have a reference MirtConnect server where we do the development of channels etc. When the development is done, we do an export using mirthsync. This export is distributed to several other Mirth servers.
Before the export can be imported on those servers, the configuration map currently used on that server and the one from the export have to be compared and merged (so that new configuration entries are added and existing entries are not overwritten by the values from the export). This task is currently difficult because the order of the configuration map entries changes from time to time, causing diff tools to not work properly.
If both configuration maps were sorted by key, it would be much easier to see the differences between them (especially when using Linux's diff tool or similar).