Warning and error message formatting cleanups.

Warning and error message formatting cleanups.

* aclocal.in (parse_arguments, main): Remove trailing period or
newline in error or warning messages, avoid capitalization of
the first word of a message.
* automake.in (check_user_variables, handle_languages)
(handle_ltlibraries, scan_aclocal_m4, scan_autoconf_config_files)
(scan_autoconf_files, cond_stack_if, require_file_internal)
(usage, generate_makefile, parse_arguments): Likewise.
* lib/Automake/ChannelDefs.pm (set_strictness): Likewise.
* lib/Automake/Configure_ac.pm (find_configure_ac): Likewise.
* lib/Automake/Options.pm (set_strictness): Likewise.
* lib/Automake/Rule.pm (define): Likewise.
* lib/Automake/Variable.pm (define, variables_dump): Likewise.
* tests/ltinstloc.test, tests/suffix11.test: Adjust expected
error message.
* lib/Automake/Channels.pm (setup_channel): Reword error message
to be the same as in msg.

Signed-off-by: Ralf Wildenhues <Ralf.Wildenhues@gmx.de>