Fix reading geoTiff

[jansule]

When reading geoTiff all grid values were set to 0.0 due to commenting out relevant code.

More specifically: band.ReadRaster() sets the values for the double array line. When not calling the function, line will only be an array of 0.0 and its values will be added to the grid, ignoring the actual values of the rasterband.

This code was commented out 9 years ago in https://github.com/eclab/mason/commit/d7a644259d6b4c02aaba8b3a787a4e72da63381c. I am not sure if this fix will have side effects on that commit.