Get rid of unused fields in output model.
The output beta needs to be scaled.  If we approximate beta2, then use
it as beta, new training data cannot make a dent.  Norm^2 of beta is
nsv if binary problem, 2*nsv if multiclass problem.  Other learning
algorithms may have different scaling.  So we will just copy the norm
from the old beta at the same number of sv.
Added gpu support.  Unfortunately gives only 50% speedup.  GPU is
detected and used automatically if present.
Fixed bug in memory calculation.
GPU optimizations.  Max is slow on GPU.  max(gather(f)) made 2.5x
faster.
gpu versions
more bugs