refactored a type if-then-else monster into a for_each loop and exlcuded a pure cout function from the converage report

fixed bug that using poll-type transfers in testable mode could sometimes lead to stalled tests or assert failures.

Relaxed the schema a bit: variables are now also allowed directly on the application level and directories and variables may be mixed in arbitrary order. Also added 64 bit integer types.

- clarified some comments

added move-assignment operators for the accessors, which is required to use move-assignment operators of modules containing accessors

Proper implementation of move constructors and move assignment operators for all module types (including tests for the assignment operator)

changed again the interface of SplitArray: the number of groups and elements per group don't have to be a template parameter, instead they are now specified in the constructor

ConfigReader: make exception what() message more elaborate when not finding a variable in the config file in get()

Extended the SplitArray modules to also allow splitting into multiple arrays of the same size. This breaks the interface of the old modules, but they were not yet used anywhere so this should be ok.

Fixed a bug that sometimes variables were read (resp. written) in groups despite they were outputs (resp. inputs). This was happening with device variables since they are bi-directional. Now no longer the information from the accessor is used whether this variable is readable or writeable, but the information from the VariableNetworkNode which direction this variable should have.