sys_io became a class, added initial version of Status class

* refactored sys_io into a class which will also handle pre-charge and other I/O stuff in the future --> a lot of changes in the file SystemIO.cpp (former sys_io.cpp), apologies.
* added initial draft of status class
* simplified and streamlined creation of singletons (local static var instead of global static var) - works reliably this way, tested it.