This is fairly flexible, so you could say 10s1h, or even 1h1h1h (which is
equivalent to 3h). Time parsing is now implemented by a single function, so
there should be no inconsistencies.
The old [[HH:]MM:]SS syntax is still supported, but not used in prompts.
Replace WGETCH() with input_char(), which works the same except it supports an
input buffer. Calling input_macro(s) sets the input buffer to 's'. The input
buffer is returned by input_char() as if it had been typed by the user.
If an error occurs (cmderr()), the input buffer is cleared.
