Fancy iterator updates to support cuda 5.0
Update doc and tests to reflect iterator (in)compatibilities with CUDA 
5.0 (and older) and Thrust 1.6 (and older).
Added ability to prefer bank conflicts versus padding arithmetic
Add compile option to build/run the short/comparo tests without
the exhaustive unit tests
First add of reduce by key
More work on reduce-by-key
- Doc updates
- More reduce value by key work
update
update
update
- Working reduce value by key.
- Fix memory alignment crash bug affecting device-wide scan-based
algorithms operating on 8B types that are 4B aligned (tile descriptor
not properly sized to 16B)
- Fix device-wide scan bug where operands for scan functors were being
applied in reverse order during look-back
- Fix block-scan bug where identity-less exclusive scans were
incorrectly including trash into the first thread's scan output
- Add thrust comparison for reduce-by-key
- Optimize reduce-by-key for when we have an identity value
Perf tune reduce by key (sm20)
Faster scan lookback.
Needs optimization for smem scan (ld/st 64)
update
Fix scan bug introduced
Added run-length encode
segmented reduction tests
update sm30 tuning
Fix for scan alignment disagreements.  Working reduce-value-by-key test
suite.