Reorg+add test for #452
Using uint* for pixel access in mode I;16 and I;32, fixes #452
reverted int32 changes
Cffi pixel access object, #248
basic benchmark shows ~order of magnitude speedup
removed initial testing
all original tests pass
more extensive testing, matches original c code
Ensuring c-api access
Getting travis into the testing loop
Passes tests on python 3.2

Reorganized to remove ImagingMemoryInstance struct, only saving the
three pointers that we need (image, image8, image32) and the x/ysize
ints.
Fixes putalpha tests

Make sure we clear the pyaccess object each time we reset the self.im
object
existing behaviour is to clamp to max, not bitmask
longer benchmark
Raising proper ValueErrors
clamping channels to 255
use cffi by default in pypy, not in c-python
trying to bust up the JIT a bit
LA, PA image modes
I;16 modes