Feature request: Add a bookmark feature

[salr]

Would like a bookmark feature similar to the one in Notepad++ that lets you bookmark a line and then use F2 to navigate back to it later. You can have multiple bookmarks in which case each F2 navigates to the next one. A bookmarked line is indicated by clicking in the margin next to the line. A blue circle identifies the line as bookmarked.

I frequently need a feature like this.