Interpolate Surface x,y data at 0.3 m spacing if x is too coarse.

Users may supply very coarse x data for surfaces. This is problematic because taking the numerical derivatives to calculate slope and curvature of coarse x spacing may result in poorly defined derivatives. This change resamples the provided x data if it is too coarse. The original data provided to the Surface object are not preserved in this case.

This figure shows the effect of this change on calculating the EFH of California jump. Note that the discrete change at the end of the table top section.

@monthubbard Have a look at this new figure and let me know what you think.

Tasks

• Some tests fail now.