Losing water when importing depth data

[jeroens]

When importing external GIS data into the EwE depth layer, any cell of a depth shallower than 0.5 is turned to land due to the integer rounding scheme of the depth layer. This is not desirable; any cell with a depth > 0 should be water.

[jeroens]

For now, water cells with a depth < 1 are rounded to 1 when imported. This is a temporary solution; eventually the depth layer should be turned to floating point data.