Use path references from the root of the project

It becomes harder to move the directory around, but it now works equally
well with both recursive and non-recursive build systems.
Move test programs out of the source tree
Import cmake/ from commit 5f82198c in opm-core
Remove opm-core specific customizations
Search and replace opm-core with dune-cornerpoint

Add dependencies that are specific for this library as well as doing
the textual replacement in the configuration file.
Ignore output from CMake build
Remove remnants of the Autotools build system
Fixed the testing programs so that they compile.

They should be moved to opm-core, though, and the classes
[Nonu|U]niformTableLinear classes removed from opm/porsol/common
(they are already in opm/core/utility.