snort plugin added
Requested changes applied.

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Requested changes committed.
Updated configuration directives.
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snort plugin: Add a bounady check when reading from the metrics array.

Also renamed "count" to "metrics_num" to make it clear that the two
relate to one another.
snort plugin: Replace strsep() (a BSD extension).
snort plugin: Improve error handling.

This prevents file descriptors and memory from leaking if something goes
wrong, e.g. the last line in the file is a comment.
snort plugin: Split the snort_read() function.

snort_read() handles the file opening / mmap part of the process.
snort_read_buffer() parses the buffer, splits the last line and calls
the submit function. This way cleaning up the FD and memory mapping is
easier in case of an error when parsing the file.
snort plugin: Assert that the configured "type" has only one data source.

Also uses the utility function from configfile.h to read the metric
definition's name.
snort plugin: Implement the "Instance" config option.
snort plugin: Free md->instance in snort_metric_definition_destroy().
collectd.conf(5): Add information about the snort plugin.
AUTHORS, README: Add Kris and the snort plugin.
snort plugin: Replace the mmap() code with the tail-code from collectd.

This makes following along a file more I/O friendly, I hope. Also, we
don't need to do quite as much buffer processing because lines are
already split for us. Also, in the unlikely case that Snort is writing
the stats file more often than collectd reads it, this will pick up all
intermediate values.
configure.in: Quote AC_LANG_PROGRAM and remove AC_INCLUDES_DEFAULT.

The latter isn't expanded anymore when quoted. There's no easy way
around this :\
tail_csv plugin: Rename the "snort" plugin to "tail_csv".

It's actually much more generic than just Snort, so give it an
appropriately generic name.
tail_csv plugin: Rename "Instance" blocks to "File".

This way the syntax of tail_csv's configuration is closer to that of the
csv plugin.
tail_csv plugin: Some bug fixes.

* Query types in the init-phase rather than the config-phase. The
  types.db is not guaranteed to be available at that time.
* Make sure the "Instance" option in the <File /> blocks is optional.
tail_csv plugin: Rename the "Index" option to "ValueFrom".
tail_csv plugin: Implement the "TimeFrom" option.