[examples.elliptic.convergence_study] SIPDG works and workds not

this is a specific setup to show the shortcomings of the SIPDG
implementation. The ADHOC one fails in testcase 3 and has problems
in testcase 4. The NEW one fails in testcase 4.

version 0.2

[dune.module] set version to 0.1

fixed some RangeFieldType vs. double issues

(the Dune::VTKFunction demands double..., we had RangeFieldType)