* subversion/clients/cmdline/main.c
(svn_cl__options): Add '--force-log' option.
(svn_cl__cmd_table): Make "commit", "copy", "delete", "import",
"mkdir", and "move" take --force-log. Also, "commit" no longer
needs --force.
(main): Parse the --force-log option. Also, instead of recommending
that folks add --force when their log message -F sources are
versioned files or -m messages are path names, recommend the new
--force-log.
* subversion/clients/cmdline/cl.h
(svn_cl__force_log_opt): New.
(svn_cl__opt_state_t): Add 'force_log' member.
* subversion/tests/clients/cmdline/log_tests.py
(versioned_log_message): Replace use of --force with --force-log.
* doc/book/book/ch08.xml
Add --force-log description, and update the usage notes for
subcommands that use it.
