Eliminate [CTRL-h] as keyboard shortcut

[terrydubois]

What to do

1. Eliminate the keyboard shortcut CTRL-h (used to show/hide participant labels).
2. When toggling participant labels on/off (via the menu), use a variable to remember the column width for participant labels, as set by the user. (Currently this information is lost each time the toggle is used.)

Background

1. Removing this shortcut is intended to reduce confusion, when users accidentally hide participant labels.)
2. The option to Show/hide participant labels remains, but is only from the View menu (a standard toggle, with checkmark).

[johnwdubois]

3. To reduce confusion, and prevent users from accidentally hiding participant labels, consider eliminating the keyboard shortcut, retaining only the View menu option. (If the shortcut is kept, then add Ctrl/Cmd H to list of keyboard shortcuts.)