ClassPairDifferenceParamsStep: learn matrix feature parameters by taking
the difference between the xs of two points of different classes.
AxisAlignedParamsStep: pass bufferIds by reference
Merged in class-pair-matrix-feature-params (pull request #25)

Use the difference between pair of points of different classes as a projection
Merge branch 'master' of https://github.com/david-matheson/rftk
Regression forests using sum of variance impurity
ClassInfoGainWalker: only compute the start entropy once
Kinect joint regression prediction
Kinect regression learner factories
Two stream walker using sum of variance impurity
Import kinect regression learners
TwoStreamBestSplitpointsWalkingSortedSteps: only include splitpoints that
are with the bounds created by taking the min/max of a subsample of the
data.  Do not allow split points on estimation points.
SliceBufferStep: prepend the original buffer name to make debugging easier
SumOfVarianceTwoStreamWalker: swap the order of ys and streamType and added
swig template
Learners: factory for consistent offline regression (nips 2013)
Biau 2008 tree learner
RandomGapSplitpointStep: Finds a random gap in the feature values and then
finds a random splitpoint in the random gap.  Impurity is calculated along
with the left and right estimates.
Kinect offset regression using Biau 2008
Assign stream with replacement or without replacement
Renamed SplitIndices to SplitBuffers
SplitBuffersI now defines how to split the buffers of a node for the two
children. The standard buffers to split is the active indices of the node.
This is implemented in SplitBuffersIndices.  Unit tests were updated.