improvements for loading into colmajor matrix
improvements for loading into colmajor matrix

added method read_colmat that will read a dataset directly into the
memory for a column major matrix. It does so by using a hyperslab
to read a row at a time

garrison/eigen3-hdf5,WaveBlocks/eigen3-hdf5,garrison/eigen3-hdf5,WaveBlocks/eigen3-hdf5