Default for fetchInMemoryState should be true

Currently the default for stateRetrieval.fetchInMemoryState is false, which means if someone writes:

<stateRetrieval />

Then fetchInMemoryState is false, so no state transfer will occur. Instead, the default should be switched to true, cos it's the essence of state transfer.

Otherwise, users are forced to write:

<stateRetrieval fetchInMemoryState="true" />