Add extra tests found online.

src/syncterm/prestest/extra.pst

+Separated glyph should not touch block
+
+Foreground color is set-after
+
+BG->FG is set-at
+
+ASCII does not affect held character
+A
+Hold on set-at, hold off set-after
+
+Clear held character #1
+
+Clear held character #2
+
+Clear held character #3
+
+
+Missing second double
+
+
+Graphics separated/contiguous state
+
+
\ No newline at end of file