======Synopsis:======
[[on]] [<modes>]set [<serial#>] [-|^]<match> { <action> }

======Description:======
This hook is triggered whenever a /[[set]] is issued.

======Parameters:======
|$0   |name of variable to be set. will be "set-error" if an invalid SET variable was specified                                         |
|$1-  |value the variable will be set to. will be "No such variable "FOO"", where FOO is the invalid SET variable if $0 is "set-error"  |

======Examples:======
To make sure [[set security]] stays on:
   on ^set "security %" {
      xecho -b You cannot set SECURITY off!
      set exec_protection 7
   }

To warn of all invalid /SET attempts:
   on ^set "set-error *" {
      xecho -b $1-. Please try again
   }