Add command to delete all switches

docs/1-user-guide.md

@@ -334,6 +334,8 @@ Note that you can't move a switch *before* the *previous switch*, to avoid break
 If you'd like to delete the most recent switch, use the `pk;switch delete` command. You'll need to confirm
 the deletion by clicking a reaction.
 
+If you'd like to clear your system's entire switch history, use the `pk;switch delete all` command. This isn't reversible!
+
 ### Querying fronter
 To see the current fronter in a system, use the `pk;system fronter` command. You can use this on your current system, or on other systems. For example:
 

docs/2-command-list.md

@@ -44,6 +44,7 @@ Words in \<angle brackets> are *required parameters*. Words in [square brackets]
 - `pk;switch [member...]` - Registers a switch with the given members.
 - `pk;switch move <time>` - Moves the latest switch backwards in time.
 - `pk;switch delete` - Deletes the latest switch.
+- `pk;switch delete all` - Deletes every logged switch.
 - `pk;switch out` - Registers a 'switch-out' - a switch with no associated members.
 ## Utility
 - `pk;log <channel>` - Sets the channel to log all proxied messages.