ELMO: Add support for digital I/O
Adding support for its digital I/O should be fairly simple assuming that it works similarly to the Infranor I/O.
This does, however bring attention to the larger problem of backwards compatibility in regards to existing ENI files. Adding or changing PDOs in the driver requires modified ENI files, meaning that existing ENI files will not be compatible. Worse yet, the program will likely not throw any errors, since the ENI file is still valid for the HW configuration (since the actual HW hasn't changed) and there is currently no way to detect mismatches between driver PDO mappings and the ENI file mappings.
Given this will be the case for any configurable device, this should be given some careful consideration. It also offers a possibility to further refine ecmasterlib's PDO API to allow more code sharing between drivers (e.g. returning single bits from a word/PDO containing the I/O state where each I/O is represented by 1 bit). This further implies that adding digital I/O support is not trivial if subtle breaking changes for existing projects are to be avoided, making this a more long term effort.