Minor label corrections for 'revert' and 'delete'

[gy-mate]

• Changed revert button emoji to ↩️ (macOS gives you this emoji when you search for undo in Character Viewer). The current one (🔙) means more like go back to the previous page, I think.
• Removed the exclamation mark from the end of Delete! (node deletion button). No other buttons on that page use exclamation marks.

[deevroman]

go back to the previous page

hmm, that's true. The only thing that bothers me is the bright color of this smiley. Most likely I will someday replace the smileys with SVG icons or move it below.

---

I'll merge this anyway. But a little later, when I add some new feature, so as not to disturb users with minor changes (unfortunately, I did not make a stable branch and users install the script from master)

[gy-mate]

Most likely I will someday replace the smileys with SVG icons or move it below.

Good idea!

I'll merge this anyway. But a little later

Thanks! :)