* Intro

This package allows adding virtual comments to files in buffers. These
comments don't belong to the files so they don't. They are saved in project
root or a global file which can be viewed and searched. The file name is
.evc.

* Virtual comments
A virtual comment is an overlay and it is added above the line it comments on
and has the same indentation. The virtual comment can be single line or
multiline. Each line can have one comment.

* Install
Spacemacs layer:
https://github.com/thanhvg/spacemacs-eos

Vanilla
(require 'virtual-comment)
(add-hook 'find-file-hook 'virtual-comment-mode)

* Commands
- virtual-comment-make: create or edit a comment at current line
- virtual-comment-next: go to next comment in buffer
- virtual-comment-previous: go to previous comment in buffer
- virtual-comment-delete: remove the current comment
- virtual-comment-paste: paste the last removed comment to current line
- virtual-comment-realign: realign the comments if they are misplaced
- virtual-comment-persist: manually persist project comments
- virtual-comment-show: show all comments of current project in a derived mode
- virtual-comment-show-delete-display-unit-at-point: delete comment from virtual-comment-show buffer
from outline-mode, press enter on a comment will call virtual-comment-go to go
to the location of comment.
Commands to link to other location (reference):
- virtual-comment-remember-current-location store the current location
- virtual-comment-add-ref add the stored location (reference) as comment
- virtual-comment-goto-location go to location

There are no default bindings at all for these commands.

* Remarks
It's very hard to manage overlays. So this mode should be use in a sensible way.
Only comments of files can be persisted.

* Test
cask install
cask exec ert-runner

* Other similar packages and inspirations
https://github.com/blue0513/phantom-inline-comment
https://www.emacswiki.org/emacs/InPlaceAnnotations

Changelog
2022-09-20
 0.5.1
 - bug fix: check for evc existing before backup
 - actually update version
2022-09-16
 0.5.0
 - won't create .evc if there is no comment for the project
 - only save data if there is change
 - if can't parse the evc file copy it to .evc.error
2022-09-12
 0.4.1 back up to .evc.bk when saving data
2022-02-28:
 0.4 virtual-comment-show-delete-display-unit-at-point
2021-11-01:
 0.03 virtual-comment-make create its own buffer to get input, no longer use read-from-minibuffer
2021-09-27:
 0.02 add location/reference