Add a new quotewrap_cols setting for external editors, default is 0 (current

terminal width) - only used when the QUOTEWRAP option is set. Common values:
0 - current behavior, wrap the quote file to the current terminal width
80 - wrap 80 columns specifically (actually, 79)
9999 - unwrap to long lines (one line per paragraph)

Actually, previously it was wrapping to current terminal width minus 4 when
QUOTEWRAP was enabled. Now, make that current terminal width minus 1
(when quotewrap_cols is set to 0).