Merge pull request #780 from andrejzverev/master

Calculate available space without reservation.
Change `f_avai` -> `f_avail`.
Sync pkg.conf.5 with the list of config variables in pkg_config.c

Sort into alphabetical order.

Fix some of the descriptive text in pkg_config.c

Fixes: #756
Merge branch 'master' of github.com:freebsd/pkg
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
Use sandbox for `rsa_verify`.
Add some guards.
Fix configuration overrides.

Issue:	#782
Reported by:	@infracaninophile
Never ever fork if version info is requested.
Partially revert case insensitivity fixes.  Apparently REG_ICASE has
quite a severe performance impact.  Therefore make the compiled-in
default case sensitive again.  Only apply the run-time default setting
from CASE_SENSITIVE_MATCH to the verbs that offer options to set the
matching type -- ie.

   annotate
   check
   delete
   fetch
   info
   install
   lock
   query
   rquery
   search
   set
   version

I think the only way to fix this satisfactorily is to use a regex library
with a saner implementation of case insensitive matching (PCRE?)
Merge branch 'master' of github.com:freebsd/pkg