EclipseWriter: Don't mingle multiple operations using arguments

This means that EclipseKeyword now never processes the data it
gets. Instead the data must be explicitly preprocessed by the calling
site using the new auxiliary functions "convertUnit()",
"extractFromStriped()", etc. This approach needs a few additional
temporary copies of the data, but given the facts that readability of
this code is much better using this approach, and that EclipseWriter
is neither a performance- nor a memory critical codepath, I don't care
too much about those temporary arrays...
EclipseWriter: add method variants taking the new instead of the old parser
Added a test for the linear solver interface.

This test sets up a simple laplace problem and solves it with the available
solvers. It assume that either dune-istl or UMFPack is present, which is
assume to be safe.
Merge pull request #532 from blattms/add-linsolver-test

Added a test for the linear solver interface.
Merge pull request #523 from andlaus/EclipseWriter_add_new_parser

EclipseWriter: add new parser
Use empty constructor to construct empty shared_ptr.

At least for g++-4.4. shared_ptr does not have a constructor
taking an integer and therefore compilation fails. Therefore we
resort statements to construct empty pointers, like
```parser_(0)```
to using the empty constructor:
```parser_()```

This patch closes #533
Merge pull request #534 from blattms/fixes-issue-533

Use empty constructor to construct empty shared_ptr.