Changed active-set convergence, now matches that of SparSNP
Changed the soft-thresholding operation back to what it is in the thesis, but functionally it's equivalent to previous version
WIP: made FMPR with gennetwork formulation the default
WIP: added fmpr2 with gennetwork for comparison
Bugfixes and modifications

* Changed convergence criteria for FMPR2 to match FMPR, results now agree with
   glmnet when there's one task
* Fixed bug in fmpr2 where gamma penalty was incorrectly applid to C matrix
* Added more plotting for Huber versions
WIP: fixing derivatives for fmpr2, based on C matrix
Small changes in variables names; changed to relative convergence test for FMPR
Updated vignette to match fmpr2 conventions
updated vignette pdf
Changed convergence testing fmpr_weighted_warm2 to relative
Deleted all old fmpr code, renamed all 'fmpr2' code as 'fmpr'
Made code less verbose by default, requires verbose>1
Added L2-fusion version of graph-guided fused lasso, optimized with SPG, both
in C and in R.
maintenance commit
Fixed computation of gradient for SPG, divide by N
Fixed bugs in gradient computation in SPG L1 and L2, we normalise by N now to
make penalties comparable across datasets
FMPR coordinate descent now matches results from SPG-L2.
Cleaned up compiler warnings
cleanup
Added divbyN argument to make results compatible with MATLAB SPG implementation