.gitignore cleanup

- Removed editor-specific temp file ignores
- Made ignores path-specific wherever sensible
Properly init/destroy monitor point mutexes
Fix timespec init for sampling delays >= 1 sec
Fixed logic when creating new datablocks

Due to this mistake, the new data blocks weren't actually being used.

This means any measurements taken up to this point where the number of
samples exceeded EML_DATABLOCK_SIZE yielded invalid data.
Drivers now initialize their own emlDevice structs

This will enable features like per-driver device naming schemes or
device descriptions.
Implemented runtime configuration

EML drivers are now configurable through an optional config file.

libconfuse is used for now to parse the configs.
This may change in the future so we can avoid one current significant
pitfall: configuration files can't define config sections for drivers
that are not compiled in, or unknown in the current version. This
precludes use of the same configuration file in different setups.

Please refer to doc/configuration.md for details.
Added initial Schleifenbauer PDU support

This commit introduces the sb_pdu driver with partial support for
Schleifenbauer power distribution units. It uses the socket API
implemented in: http://schleifenbauer.eu/downloads/API/

PDUs are queried over TCP/IP. They are not autodetected and should be
declared in the sb_pdu section of the configuration file:

	sb_pdu {
	  device ourpdu {
	    host = 10.0.0.3
	    port = 7783
	  }
	}

The driver depends on libcrypto for the RC4 encryption. Although perhaps
disproportionate, this dependency may be useful in the future if support
is added for any other devices using encryption.

Current limitations and known issues:
- only one PDU module per configured device is (properly) supported
- socket operations are blocking for now
- the implemented measurement caching introduces avoidable inaccuracy
- existing pdu-level energy counters are not used
Extend tests to 3 runs of 10 seconds by default

This is better suited to testing slow devices (such as sb_pdu) and
measurements encompassing multiple data blocks.
Clarified required and optional dependencies
Changed NEWS and ChangeLog generation format
Bump version to 0.2.0