Add ability to read from options file to check_mysql_query.c

This is the same code that was added to check_mysql.c in 5ed7194.
Add additional usage data for new options in check_mysql_query.c
Rename ENV variable, keep backward compatibility

Rename NAGIOS_PLUGIN_STATE_DIRECTORY to MP_STATE_DIRECTORY
Clean up parse_ini error messages, add missing newlines
Ignore MP_STATE_DIRECTORY in suid plugins

If a plugin still has suid privileges at the time np_enable_state() is
called, the MP_STATE_DIRECTORY environment will be ignored.

There is no need for a NEWS entry as no suid plugins use np_enable_state
yet.
Fix tests with an empty NPTest.cache file

The NPTest.cache cannot be loaded when empty, and this prevents
getting the data and populating the file. This patch skips the file when
empty as if it didn't exist.
And release notes for previous change (MP_STATE_DIRECTORY)

The change has also been updated in
https://www.monitoring-plugins.org/doc/state-retention.html
Rename MP_STATE_DIRECTORY to MP_STATE_PATH
check_dig: fix wrong IPv6 arguments order
Merge pull request #1200 from awiddersheim/add_file_options_mysql_query

Add ability to read from options file to check_mysql_query.c
Clarify check_mysql test prompts

Also default to "-u test -ptest" which are default MySQL accounts only
missing the prescribed privileges.

The database is no longer specified as it is not used.
If wanted is should be its own parameter/tests.
check_http: timeout problem on http redirection case
(patch suggested by Artavazd Mertarjyan)

On the HTTP redirection case, plug-in continues work ignoring timeout
specification. Plug-in resets the timer after first response. So, I
suggest to set new timer to the remainder of timeout value.

Closes: #826
Closes: #1167