seq(1): Consistently include 'last' for non-integers

The source of error is a rounded increment being too large and thus the loop
steps slightly past 'last'. Perform a final comparison using the formatted
string values (truncated precision) to determine if we still need to print
the 'last' value.

PR: 217149
Submitted by: Fernando Apesteguía <fernando.apesteguia AT gmail.com>,

		Yuri Pankov <yuripv AT icloud.com> (earlier version)

Reported by: Martijn Dekker <mcdutchie AT hotmail.com>
Sponsored by: Dell EMC Isilon