Improve usability of head(1) and tail(1):

• Consistently support -q (quiet) and -v (verbose)
• Allow specifying numbers with SI prefixes supported by expand_number(3)
• Remove 2^31 limit on lines for head(1)

MFC after: 2 weeks
Reviewed by: lwhsu, pauamma, gbe
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D35720

(cherry picked from commit 643ac419fafba89f5adda0e0ea75b538727453fb)