Markers not being saved

[gdude2002]

This seems to be an issue that has existed for years with Dynmap in general. Maybe we can get it ironed out?

Minecraft: 1.10.2 Forge: 12.18.3.2221 Dynmap: 2.4

Steps to reproduce

1. Open Dynmap in your browser.
2. Ingame, make a marker set and add markers to it using /dmarker as described on the dynmap wiki.
3. Note that the markers are visible in your browser.
4. Reload the page.
5. Note that the markers are no longer visible.
6. Open dynmap/markers.yml and note that there are no markers in the file.