A few minor spelling fixes.

Also, remove a stray email address that leaked through our
address-removal pass a while ago.
Don't put leapseconds.awk in tzdata tarball.

This harmless bug was introduced in release 2014f, which distributed
leapseconds.awk in both the code and the data tarballs.
It's code, so it should be in the code tarball.
* Makefile (DATA): Omit leapseconds.awk.
(check_character_set): Omit redundant check of $(LEAP_DEPS).
Minor spelling, accent, and spacing fixes.

In particular, this patch is makes the commentary more systematic
about preferring "time zone" to "timezone" except when quoting someone
else or when talking about code that uses "timezone".