Merge pull request #19 from lawinslow/master

SubsampleGLM Efficiency improvement
Added year to GetIceOn/Off methods.

Important because the old way might have incorrectly dealt with ice-on after Dec 31st, depending on how you supplied data. Now, it searches for the max temp within that year, then goes forward or backward from there. This is somewhat more flexible, though we may need to change this for southern hemisphere (though maybe not, might work well enough).
Removed some redundant functions between GLMnetCDF and GlmPhysicalDerivatives.
Further fixes to getIceOn/Off methods