src/common/tls.c: Add missing "break" statement

If the peer aborted the TLS shutdown, the check_tls_error() function
generated an additional, bogus warning message due to a missing "break"
statement.
Add "authorize" section for PING-only access

Add an example "authorize" section which shows how to allow clients to
talk to the server without allowing them to submit anything to the
command file.  This might be useful for monitoring the server.
m4/aio.m4: Use AIOLIBS when testing POSIX AIO

Since commit 60ff499, the linker options required to use the POSIX AIO
API are saved into AIOLIBS instead of into LIBS.  This broke our
Autoconf test whether POSIX AIO actually works.
Only use the command file if it's a named pipe

Check whether the command file is a FIFO after opening it.  If it isn't,
close it again, log a warning message, and retry opening it later on.
Use AES256-CBC instead of RC4 by default

We used the PSK-RC4-SHA cipher suite by default, since the CBC ciphers
are broken in OpenSSL 1.0.1d.  However, many other applications don't
work (properly) when linked against 1.0.1d either, and it was quickly
replaced with 1.0.1e (which fixes the issue), so the number of 1.0.1d
users is probably very small.  Therefore, it should be safe to use the
PSK-AES256-CBC-SHA cipher by default.
PROTOCOL: Clarifications regarding PUSHed commands

Explicitly note that PUSHed "monitoring commands" shall not be
CRLF-terminated, and that embedded newline characters and backslashes
must be escaped.
Log a notice when (re)opening the command file

The server should log a notice when opening the command file succeeds
after having failed before.
TODO: Add a wish list item

The client should support talking to multiple servers.
etc/nsca-ng.cfg: Add a default "authorize" section

Add an "authorize" section which lets the server start out of the box
(instead of bailing out because the user didn't specify an "authorize"
section).  The new configuration still doesn't permit clients to submit
anything to Nagios (it just allows authenticated clients to talk to the
server), so the client will spit out a "not authorized" message until
the user edits the nsca-ng.cfg(5) file.
etc/nsca-ng.cfg: Give better examples

Improve the clarity of the authorization section examples a bit.
configure.ac: Set AC_CONFIG_MACRO_DIR()

The Autoconf manual suggests to specify the AC_CONFIG_MACRO_DIR(), as it
might be used "by future versions of commands like autoreconf that trace
macro calls".
Mark Markdown files as such for Vim

Specify "filetype=markdown" in the Vim modeline of Markdown files.
PROTOCOL: Improve wording a bit

Slightly improve the wording of the description of the PUSH request.
Make Clang happy

Fix two minor compiler warnings.
COPYING: Slightly improve wording

Improve the wording in the COPYING file a bit.
contrib/debug_server: Fix send_nsca.cfg(5) parsing

Quote the argument to the "eval" call that parses the configuration
file.
contrib/downtime: Fix our timestamps

The timestamps must be submitted as the number of seconds since the
Epoch.
contrib/invoke_check: Fix our send_nsca(8) call

The invoke_check script doesn't feed send_nsca(8) with "raw" commands,
so specifying the "-C" option was incorrect.
NSCA-ng 1.0
Merge tag 'v1.0' into debian

NSCA-ng 1.0

* tag 'v1.0':
  NSCA-ng 1.0
  contrib/invoke_check: Fix our send_nsca(8) call
  contrib/downtime: Fix our timestamps
  contrib/debug_server: Fix send_nsca.cfg(5) parsing
  COPYING: Slightly improve wording
  Make Clang happy
  PROTOCOL: Improve wording a bit
  Mark Markdown files as such for Vim
  configure.ac: Set AC_CONFIG_MACRO_DIR()
  etc/nsca-ng.cfg: Give better examples
  etc/nsca-ng.cfg: Add a default "authorize" section
  TODO: Add a wish list item
  Log a notice when (re)opening the command file
  PROTOCOL: Clarifications regarding PUSHed commands
  Use AES256-CBC instead of RC4 by default
  Only use the command file if it's a named pipe
  m4/aio.m4: Use AIOLIBS when testing POSIX AIO
  Add "authorize" section for PING-only access
  src/common/tls.c: Add missing "break" statement

Conflicts:
	contrib/README