Add --enable-verbose option, disabled by default.

Still need to update the documentation.
Merge branch 'develop' into optional-verbose
Merge branch 'develop' into optional-verbose
Merge branch 'develop' into optional-verbose
rec_track.c:609: missing comment for __ovfl_txnc_dump
Make all of hte enable patterns the same; minor rewording of the verbose
option, not sure why, but "flags" seems wrong, use "Enable verbose message
configuration." instead.
A somewhat different approach to --enable-verbose: inline __wt_verbose()
and the test of the verbose flag, remove all of the WT_VERBOSE_XXX #defines
other than WT_VERBOSE_ISSET.
Verbose is only available from --enable-verbose builds, remove
the test_reconfig_verbose test, it's likely to fail.
Merge branch 'optional-verbose' into optional-verbose-inline
Merge branch 'develop' into optional-verbose
Merge branch 'optional-verbose' into optional-verbose-inline
Tidy up unused session parameters in verbose macros.
Merge branch 'optional-verbose' into optional-verbose-inline

Conflicts:
	src/include/misc.h
	src/os_posix/os_fallocate.c
Merge pull request #993 from wiredtiger/optional-verbose-inline

A somewhat different approach to --enable-verbose: inline __wt_verbose()
Merge pull request #992 from wiredtiger/optional-verbose

Add --enable-verbose option, disabled by default.