Fix some spelling.
Merge pull request #781 from Absolight/fix-man-page

Fix some spelling.
Fix typo.  Now the text at least makes sense.
Add a CASE_INSENSITIVE_MATCH pkg.conf variable (boolean)
defaulting to false.

Change the compiled-in default to false as well.

Set the run-time default for match case sensitivity style from the
pkg.conf value.
Document the new pkg.conf CASE_SENSITIVE_MATCH setting.
It's CASE_SENSITIVE_MATCH everywhere else.  Whoops.
Stupid typo.
Everywhere there is an option to match a package name (substring,
regexp), add a -C option to force the match to be case sensitive.

Group the 'match' options [-Cgix] in usage() messages.

Sort options in the getopts() call and occasionally the corresponding
entries in the case statement.
Update man pages to add description of new -C 'case sensitive match'
option.

Group the "match" options -Cgix or -Cegix together in the synopsis.

Fixes: #737
Merge branch 'master' of github.com:freebsd/pkg
Merge branch 'master' into pkg-url