Deck: mark numKeywords() and getKeywordList() as const

this was probably an oversight...
add the ROCKOPTS keyword

because to properly initialize the ROCKTAB table, it is required...
add the IMPTVD and IMKRVD keywords and table classes

basically they are just renamed copies of the EN* variants...
remove RockTable

because ROCK is not a table keyword
remove the PvtwTable

because PVTW is not a table keyword...
remove PvcdoTable

because PVCDO is not a table keyword.
make all table classes default constructible

this allows to store them in std::vectors, but requires to call the
init() method after construction...
make it possible to evaluate some tables using linear interpolation

... and constant interpolation at the fringes. this kind of evaluation
in between sampling point only makes sense for tables where the first
column is strictly monotonic, though.
tables: propertly handle defaults and monotonicity of columns

for some kinds of tables this means linear interpolation for some
columns, constant for other columns and some tables do not allow to
specify default. Since there is no clear rule, this patch involved
checking the reference manual for every single f****** table keyword
plus some guess-work if the reference manual is unclear about
monotonicity and/or defaults.
add table classes for RSVD and RVVD

these keywords are used by opm-core, albeit currently in a
"bare-metal" way.
endpoint scaling tables: make the bare-metal getColumn(index) method public

it is _strongly_ encuraged to use the properly named methods to access
the respective columns, but opm-core's current endpoint scaling code
makes it hard to use these...
EclipseState: initialize and expose the tables which are featured by the deck

since this code is becomming a bit tricky, it is now recommended to
use the tables of EclipseState instead of trying to initialize them
yourself...
tables: make them instantiable exclusively by EclipseState

since tables can be tricky, we now enforce that the compiler bails out
if the user tries to instantiate a table class manually.

Note that a bit of trickery is needed to keep the low-level unit
tests working...
tables: remove trailing underscores from the protected and private methods

opm-parser does not follow this convention...
move the table classes from .../Utility to .../EclipseState/Tables