Improve ordering of entries in Edit REPL Commands window

[imrekoszo]

At present, this window lists repl commands in the order they were added (which appears to match the order they are in the xml file where they are stored). It is not currently possible to reorder entries in this view.

This is not very user-friendly when one has many repl commands defined. It isn't possible to find a command or make related commands appear close together using the tool window.

Repl commands are an extremely awesome feature and being able to better organize them would make them even better.

Related: #1415