[evolution-patches] Add the possibility to hide the GtkHTML Edit toolbar

[Jan Holesovsky <kendy suse cz>]

Hi,

When composing a mail, the GtkHTML Edit toolbar is highly annoying for
me ;-) - I write only plain-text mails, and the toolbar only wastes
place on my screen.

The attached patch adds the possibility to hide it, using the same menu
as where From/To/CC/BCC can be hidden (View).

Comments [or commit & push ;-)] appreciated.

Thank you,
Kendy