patch 8.0.1424: the timer_pause test is flaky on Travis

Problem:    The timer_pause test is flaky on Travis.
Solution:   Accept a longer sleep time on Mac.

patch 8.0.1423: error in return not caught by try/catch

Problem:    Error in return not caught by try/catch.
Solution:   Call update_force_abort(). (Yasuhiro Matsomoto, closes vim#2483)

patch 8.0.1422: no fallback to underline when undercurl is not set

Problem:    No fallback to underline when undercurl is not set. (Ben Jackson)
Solution:   Check for the value to be empty instead of NULL. (closes vim#2424)

patch 8.0.1421: accessing invalid memory with overlong byte sequence

Problem:    Accessing invalid memory with overlong byte sequence.
Solution:   Check for NUL character. (test by Dominique Pelle, closes vim#2485)

patch 8.0.1420: accessing freed memory in vimgrep

Problem:    Accessing freed memory in vimgrep.
Solution:   Check that the quickfix list is still valid. (Yegappan Lakshmanan,
            closes vim#2474)

patch 8.0.1419: cursor column is not updated after ]s

Problem:    Cursor column is not updated after ]s. (Gary Johnson)
Solution:   Set the curswant flag.

patch 8.0.1418: no test for expanding backticks

Problem:    No test for expanding backticks.
Solution:   Add a test. (Dominique Pelle, closes vim#2479)

patch 8.0.1417: test doesn't search for a sentence

Problem:    Test doesn't search for a sentence. Still fails when searching for
            start of sentence. (Dominique Pelle)
Solution:   Add paren. Check for MAXCOL in dec().

patch 8.0.1416: crash when searching for a sentence

Problem:    Crash when searching for a sentence.
Solution:   Return NUL when getting character at MAXCOL. (closes vim#2468)

patch 8.0.1415: warning for unused function without timers feature

Problem:    Warning for unused function without timers feature.
Solution:   Add #ifdef. (John Marriott)