only allow a single boost via hotkey - fixes #467 #468
As usual, have to write the same thing four times☹️ The parentheses around `q` tell the hotkey/keymap code to ignore auto-repeat events (which works fine in Chrome but not in Firefox, I reported the bug https://bugzilla.mozilla.org/show_bug.cgi?id=1900397 ) In addition, I've added a guard variable that is true while calling the backend to boost/renote, and false otherwise. This way, even in Firefox we don't spam-boost. Unboosting is still *only with the mouse*, I have not added that functionality.