Remote edit external editor bug on MacOS

[Kaspar-Metsa]

Steps to reproduce:

1. Set Text Edit/Sublime as default editor on your mac for .txt files
2. Use "open -W -n -t" for remote editing external editor which chooses the default editor set in step 1. Can also choose a text editor with "Browse"
3. Do a remote edit change on anything
4. Click Save

Expected behaviour:
Mume closes edit session after Save

Actual behaviour:
Edit session in MUME does not close. Only way to exit: terminate the sublime/text edit process or relog the MUME character

[nschimme]

MMapper checks if Sublime was closed rather than polling if the file got changed. We could do this on first save, but then if you keep editing MMapper won't be aware of the further changes.