vfs:  Add terminal_method_set
vfs:  Add terminal_methods to method superset
vfs:  Add terminal_methods() member to filehandle
Merge branch 'terminal_method_set'
Genie:  Uninline TerminalHandle constructor
Genie:  Define terminal hangup method
vfs, Genie:  Add hangup() primitive
Genie:  Use hangup() to disconnect window terminal