updated for version 7.4b.020
Problem:    "g~ap" changes first character of next paragraph. (Manuel Ortega)
Solution:   Avoid subtracting (0 - 1) from todo.  (Mike Williams)
Added tag v7-4b-020 for changeset 46cf49cc9289
updated for version 7.4b.021
Problem:    Pressing "u" after an external command results in multiple
	    press-enter messages. (glts)
Solution:   Don't call hit_return_msg() when we have K_IGNORE. (Christian
	    Brabandt)
Added tag v7-4b-021 for changeset 059c8a4b103f
updated for version 7.4b.022
Problem:    Not waiting for a character when the tick count overflows.
Solution:   Subtract the unsigned numbers and cast to int. (Ken Takata)
Added tag v7-4b-022 for changeset d5d6b78cff09