Sst complex2

This fixes a number of issues, but doesn't test as many as it should yet. Principally, it fixes an oversight where a bit of code that is used to adjust the types of scalar variables in FFS marshaling wasn't updated to include complex types. It turns out that this code also wasn't correctly handling doubles in some circumstances, resulting in the problems of issue 856. @tneuroth Currently only testing scalar doubles written by rank 0. Should extend to other types, other ranks writing, etc.