Bug 568167: [RJ-Data] Change hierarchy of factor stores (RFactorStore
no longer extends RIntegerStore) fixing nullable definition of
RStore#getChar

Follow-up-to: d3633e3402e37b80b615fb2aadbf93b1d3a8dae2
Change-Id: I78375a313a3db909af79b27f36512dcdff66b028
8 files changed