Fixed radix join's handling of partitions and delta

Previously, the radix join would assume that the table is a row store.
It would use the offset of a column in a table as the offset in the
attribute vector. That will fail for most other situations, especially
with a pure column store.

Furthermore, the handling of delta was fixed. The old cold did not
retrieve the actual attribute vector of the delta but the main instead.
Added test for column store handling of radix join
Added failing test for radix delta
Fixed failing radix delta test

RadixCluster now iterates over entire table instead of just main.
Instead of main dictionary, lookup for value ids in delta is now
performed with the delta dictionary (duh!)
Acquiring the delta dict by dict of last row
Committed todos