Fixes #151

fixed not creating some of the application varibales with wait_for_new_data despite they were specified as push inputs

Updated to use the new ReadAnyGroup instead of the old readAny function. Some tests are still hanging or failing (mostly due to shutdown issues)

necessary changes for the latest DeviceAccess update (readAsync() return type no longer a reference, and other related changes)

update for interface change in DeviceAccess: TransferElement::write() has now the version number as an argument

- use this return type in testable mode to detect when a queue overflow happened (testable mode counter should not increase in that case)

use the new readLatest(), which has been added to the latest DeviceAccess version, to implement the naturally expected behaviour when using a push-type variable with a poll-type accessor

fixed blocking read transfer for the constant accessor: should only return on first read and then block forever

Read all application inputs once before starting the module threads, so the initial values are correctly present.

For this purpose, additional changes were necessary:
- Added support for constant values as feeders and consumers (just ignore the writes)
- Connect all unconnected application accessors to constants after defining the connections and before creating the implementations
- Renamed the user-overridden function "initialise()" into "defineConnections()", since more actions are now necessary during initialise().
- The connections are now made (i.e. the implementations are created) during the initialisation phase