Use match_check_event instead of deprecated match_check

[Egmont Koblinger]

As of VTE version 0.44, Vte.Terminal.match_check() is deprecated, Vte.Terminal.match_check_event() should be used instead. The latter one is available since VTE version 0.38, that is, VTE library version 2.91.

VTE 0.44 implements "super smooth scrolling", that is, with the touchpad the contents can be scrolled back pixel by pixel, rather than row by row. Vte.Terminal.match_check() by design cannot cope with this situation and potentially examines the wrong line (off by one). Using Vte.Terminal.match_check_event() eliminates this problem.