Dbaroli/fix ellipsoid function

See merge request !1

example of use Mesh with Hole circular with custom FunctionNorm type; number of nodes for lines and number of nodes in inner rings are very important for good representation of circle and mesh refinement

assert on dim of Lines; assert of ringNodes; bug fix on NormFunction if it is modify the type from user or the NormFunction itself

Additional files in tutorials/statics demonstrating the basic use of mafe for 2d elasticity and plate bdening problems.

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