Grid properties: get rid of the dimension string for integer properties

this uses a small amount of template magic, to automatically change
the API of the GridProperty class depending on wheter it is
instantiated for double or for int.
add definition for the ROCKTAB keyword
fixed: keep a copy instead of a reference

storing string references are not a good idea, since temporaries are
often used. fixes RawRecordTest on my box
Merge pull request #233 from andlaus/add_ROCKTAB

add definition for the ROCKTAB keyword
Merge pull request #236 from akva2/no_references_for_you

fixed: keep a copy instead of a reference
Keywords for capillary pressure scaling.

Four new keywords PCW/PCG/IPCW/IPCG and fixing SWATINIT.
Correct dimension is 'Pressure'.
Merge pull request #237 from osae/pcScaling

Keywords for capillary pressure scaling.
Merge pull request #230 from andlaus/remove_dimensionString_from_integer_grid_properties

Grid properties: get rid of the dimension string for integer properties
add some missing transmissibility multiplier keywords

and add a dimension to MULTZ
property operators: add quite a few additional keywords

These are all keywords which are used by the Norne deck within some
property modifiers plus all variants of these. (sans the variants for
radial grids which are completely pointless IMO.) The chances that
keywords which have not been added yet can also be used are very close
to 100%, though.

Note that the default values for these keywords are currently
incorrect as the Eclipse RM states that the values must be looked up
in their corresponding table if the keyword is left unspecified (see
e.g. the documentation SWU). This probably means that we need to
implement "ghosty" keywords which magically appear if they have not
been explicitly specified or maybe we should only provide them in
EclipseState to be able to do the context dependent table look-up
"vodoo"...
Merge pull request #232 from andlaus/modifiers_add_more_supported_keywords

Modifiers add more supported keywords
change construction of ParserKeyword objects to the factory paradigm

this makes it more explicit what the object is supposed to represent.
Merge pull request #239 from andlaus/ParserKeyword_to_factory

change construction of ParserKeyword objects to the factory paradigm
Fixed bug in extending TOPS vector.
Added EclipseGrid::getCellVolume() and getCellCenter()
Added Parser test of deck with TOPS keyword.
Merge pull request #238 from joakim-hove/EclipseGrid-TOPS

Bug when creating ECLIPSE grid from TOPS keyword.
add support for parser keywords specifying to multiple deck keywords

Say hello to the complete set of well, region, field and group output
specifiers soon...
avoid illegal internal names in the MULT keywords

before this, the variants with the trailing minus were just silently
ignored, and even if they were not, the code generator would have
produced illegal code, because the keyword name is used for a C++
variable there, i.e. the names needed to be valid names in the C++
sense. "Happily", these the former bug canceled the latter, so the
build went through...

now, there is only one internal keyword called "MULT_XYZ" which
matches on all possible variants which are allowed in a deck. The
mechanism used is a deck name list...