Bug Fix: Ordering of code leading to infinite loop

Swapped the order of 2 lines of code. Without this fix, an infinite loop occurs since `offsetSeek()` executes `createIndex()` which executes `offsetSeek()` ... etc. if `self.recordIndex is None`

To see this for yourself do the following:
1) Without this bug fix, execute `python radDataTypes.py` and watch as your screen forever fills with `reached end of data` messages.
2) Install bug fix and then execute `python radDataTypes.py`