Add preferred phase to Well class.

This entails:
 - Adding a new data member of type Opm::Phase::PhaseEnum.
 - Adding method getPreferredPhase().
 - Adding extra constructor argument.
 - Modifying constructor call in Schedule::addWell().
 - Adding unit test for the new preferredPhase property.
 - Modifying constructor call in all the well unit tests.
Merge pull request #172 from atgeirr/add-preferred-phase-to-wells

Add preferred phase to Well class.
Will temporarily convert double -> float before instantiating an ERT eclipsegrid.
Added PROPERTY GENERATED TRUE to generated file, to avoid cmake halt. File is always generated.
Merge pull request #175 from flikka/fix-generatedfile

Added PROPERTY GENERATED TRUE to generated file, to avoid cmake halt. Fi...
Moved test of valid keywordname to ensure that e.g editor backupfiles are not parsed.
The createDefaultkeywordlist program will create the generated-source/ directory if it does not exist.
Removed top level CMakeLists.txt creation of generated-source/ directory.
CMake beautification.
Large changes to createDefaultkeywordlist: Will create both tests and testSource in one pass. The special sorce code to create test source is removed. The test source is marked with Generated_source attribute.
Added two dependencies to generated files, to avoid potential build failures due to premature use of them
Merge pull request #176 from joakim-hove/build-fixes

Build fixes
Merge pull request #174 from joakim-hove/double-float-grid

Will temporarily convert double -> float before instantiating an ERT ecl...
add PVCDO keyword and fix typo pvdco -> pvcdo

this is used in opm-core but I doubt that these code paths have
actually been tested recently because the parser would have thrown up
as soon as it had encountered PVCDO...
Added default values for keywords ENPTVD/ENKRVD

Setting defaulted parameters to -1 for later identification.
The ParserKeyword->parse() method will throw if the raw input argument is not finished.

Requires several changes to assure that the rawkeyword instances are
marked as finished before reacing the ParserKeyword->parse method.
Added boolan flag scalar = true to DeckItem.

The purpose of this flag is to keep track of whether a keyword is
supposed to have only one element, i.e. scalar, or several. The
defaultApplied method only makes sense in the case of scalar items, this
method will now throw if it is called on a non-scalar item.
Verified behaviour of defaults (i.e. *) for multivalued items.
Merge pull request #179 from andlaus/add_pvcdo_keyword

add PVCDO keyword and fix typo pvdco -> pvcdo
Merge pull request #178 from joakim-hove/data-with-default

Data with default