Ressurect Minor Mode

[titaniumbones]

In the context of #29, consider bringing back a minor mode with a few additional keybindings, e.g. for attachment functions, etc. The minor mode can just be set e.g. in the first magic line of a file, with say

# -*- eval (org-grading-mode 1) -*- #

[titaniumbones]

work is in progress on this. It's not great though.