Ignore IntelliJ Idea project files.
Ignore IntelliJ Idea modules.
Initial checkin of ImmutableArray class, which replaces WrappedArrayIndexedSeq.

WrappedArrayIndexedSeq was not specialised.  The new ImmutableArray class does not implement
IndexedSeq directly and can be specialised.
Replace .toByte with utility function that creates Bytes.
BinaryFormat should not need to know its ProcessorType (decoupling).
Merge branch 'feature/immutablearray' into develop