GeometryCoordinates2D not masked out correctly for complex shapes

[JanisGeise]

When using the GeometryCoordinates2Dclass to mask out geometries based on coordinates, it may happen that the geometries are not masked out correctly.

This happens when a cell has nodes within different parts of the geometry object. For example, consider a C-shaped geometry in 2D. When a cell now has 2 of its nodes in the lower part of the C and 2 nodes in the upper part, it will be removed from the grid although the middle of the cell lies within the flow field.

For example, the geometry may look like this:

----------------
|  x       x    |
|    |----------
|    |
|    |_________
|  x      x    |
---------------

The x denote the nodes of the cell and the dashed lines --- the geometry. Since all nodes are within the geometry, the cell will be removed from the grid, resulting in a more box-shaped geometry:

----------------
|              |
|            |-
|            |
|            |_
|              |
---------------

There is currently no fix for that other than slightly changing the size and/or position of the geometry object.