Forward gravity vector to the properties object

The upscaled version of the properties contains the macro-scale gravity,
so this must be made available all the way from the wrapper and down.
Add common interface code from rel.perm. to cap.pres.

The code to find the interface from the upscaled saturation is the same
for the rel.perm. and the cap.pres. code, but these are in two different
methods, thus it has to be duplicated.

This could be refactored into something that does all the querying first
and then called some other routine, but I don't think it is worth it.
The runtime cost of querying cannot be removed without a redesign.
Capillary pressure due to hydrostatic difference
Use constant for number of phases

There are too many assumptions about two-phase (saturations should
sum to one, hard-coded number of phases returned) that the code as
it is should be able to run with more, so it might as well be a
constant.
Add contribution from fine-scale entry pressure
Derivatives of the upscaled capillary pressure
Comment on the terminology used when referring to phases
Merge pull request #21 from rolk/021_cappres

Upscaled capillary pressure (incompressible case)
Pass well list from 3D deck to the upscaling object

Extend the interface of the upscaling object so that it retrieves a
list of existing wells in the full model and provide similarily a list
of wells in the upscaled version (since the grid has changed).

Currently, there is no implementation for these methods, just the
declaration.
Create a clone of the well list to operate on

We don't want to make changes in the list submitted to us (we don't
know how *many* times it is being submitted to us, meaning we wouldn't
know if a previous instance of ourselves had already changed it, so
it is a dangerous thing to assume), so make a clone to work on.
Translate the cell indices of the well perforations

At the same time, check that the assumption that there is only one
well in each column is not being violated.
Wrapper uses well list translated to top surface

Wells are translated from the full grid to the top surface grid. The
state is kept the same, because it is the same number of wells, they
are just located in a "different" place (squashed to 2D).
Merge pull request #22 from rolk/022_wells

Translate well list from fine grid to top surface (squash to 2D)
Use common denominations for phase positions

The rest of the simulator framework expect the phases to be in the
order listed by this enumeration, so we should be a nice citizen and
do that too.
Setup internal methods to do pres. and sat. upscaling

These functions are handled in the props object since it already has
access to the data which is necessary to do the upscaling.
Upscale pressure assuming vertical equilibrium

Integrate the pressure gradient in the vertical direction, using the
discretized framework we already have in place.
Upscale saturation by integrating vertically

We ignore variations of the area in each block; this may cause trouble
further down the line.
Merge pull request #23 from rolk/023_init

Upscale initial domain values of pressure and saturation
Upscale size-independent properties

Some properties are independent of blocksize (such as the volumetric
source term) in the sense that they should not be averaged, but simply
summed to find the upscaled version.

This method encapsulate the index retrieval and summation, and keeps
us from having yet another layer of indirection. An outer loop is
still needed in order to keep working on each column, as the other
methods in the interface.
Expose a way to get the upscaled source term

Upscaled source terms are calculated from the corresponding information
for the coarse grid, and a method made available to get these data back
out again.

This method make a copy of the data, so if they change, then the
upscaled values are not updated.