DataArray: Add [get|set]DataDirect methods
DataArray: go via [set|get]Data for all overloads
DataArray: move [set|get]Data impl. to cpp file
DataArray::getData: support polynom while reading
[test] check polynom application while reading
Move applyPolynomial from DataArray to util
util::applyPolynomial: take vector by const-ref

Not just ref.
DataArray::getData: make poly vector<double> const
DataArray: include cstring header for memcpy
Merge pull request #378 from gicmo/polynomial

Apply the polynomial coefficients when reading data

LGTM, thanks.