Re-editing an .org file invalidates ts-parser

[tonico]

When I :edit an .org file for the first time then the org-bullets are applied. However, if I :edit the same file again then the org-bullets are not applied.

I guess the ts-parser is no longer valid when this happens. Adding the following code in get_mark_positions() fixes this for me:

  if not parser:is_valid() then
    parser:parse()
  end

[akinsho]

@tonico I haven't experienced this problem myself I think but please try #31, it's a stab in the dark

[akinsho]

fixed by #31