Jlibsedml and SedmlImporter should be upgraded to be able to read and appropriately handle v1.5

[CodeByDrescher]

Currently, we do a custom version which can process up to SedML level 1 version 3 (we only support L1V2 features).

We do not need to support the features at each tier, but we should be able to properly parse and handle the files, and not delivery undefined behavior.

[jcschaff]

moving this one to Queued, we at least need for SED-ML documents marked as version 1.5 to not fail. Lucian needs this soon.