Ability to add markers to savestates and/or frames

[vadosnaprimer]

When doing complex non-linear comparisons across several branches, it's very easy to get lost, especially if you have to keep creating newer branches just to have backups. Without notes which branch is what it's very hard to figure out which to go back to in order to tweak the strats, and what game state they contain.

To display those notes, the easiest way would probably be to simply show a popup when hovering on a frame that has the branch with a note.

In my use case, adding notes just to savestates/branches would be enough, but maybe users would want to add markers to regular frames. Maybe overall that would be a better solution, since to add/display the notes, actions for branches and frames would be the same, and being able to add them to any frame would cover more use cases.

[vadosnaprimer]

Solved in current master.