Every sensor stores its full MQTT-topic now

Add possiblity to specifiy plugins in the global.conf
Rename plugins to libdcdbplugin_pluginName.so
Add version number to plugin-names

Remove readme.txt from perfevent

Add possibility to compile with symbol DEBUG (use "make debug")
Minor fixes and improvements to debug-output

Add missing -rdynamic flag to the linking of dcdbpusher
Fix double-free error when destructing a Template-Sensor

Finished rework of sysfs-files.
Adapted and improved various other involved classes.
TODOs remaining:
-adapting Makefile for automated compilation of librarys
-solving runtime errors when trying to run dcdbpusher with sysfs

Removed no longer required files from SYSFSSensor
Renamed SYSFS to Sysfs
Introduce Configurator-base class, derive SysfsConfigurator from base-class

Add generic Sensor-base class
Rework dcdbpusher + MQTTPusher to use generic base class

Add perfpusher-files.
Together with sysfspusher this should be enough for a start. Add other pushers later when dcdbpusher is working.

Add sysfspusher-files

MQTT Pusher Improvements

See merge request dcdb/sysfspusher!1

(former only one PerfCounter for all CPUs)
Add check if MQTT-Topic is assigned twice

Deleted test.c as it was just a reminder-file.
Add readme.txt as kind of (incomplete) documentation
Various TODOs remain. Also some polishing could be required.

Some bug-fixes and improvements