* src/vte.h src/vte.c: Added default signal handlers to VteTerminalClass
	(#137961).  [NOTE: ABI change.]
* src/vte.c(vte_terminal_configure_toplevel): don't re-invalidate everything,
	apparently unnecessary (#122243).  Might need to back this out if I
	ever remember what specific combination of software and versions
	prompted its addition in the first place.
* src/vte.c(vte_terminal_class_init): tell gettext that messages retrieved
	from this domain should be returned in UTF-8 (#139542).