Added iset() method to GridProperty
Added GridProperty::multiplyWith( )
Added containsNaN() method to GridProperty
Added keyword MULTPV
Added post processor to GridProperty
Added postprocessor properties to scatter from top.

For the petrophysical properties PERM? and PORO only the top layer must
be specified, cells further down can be copied from the layer
above. This functionality is implemented with a GridProperty
postprocessor.
JSON keyword definitions: add a "sections" item

this which specifies the allowed sections of the keyword. (surprise!)
ParserKeyword: add the glue code so that it knows its sections
JSON keyword definitions: make the "sections" item mandatory

the empty list can be used which means that the keyword may occur in
any section. (which is useful for e.g. section delimiters.)
Extend deck grooming functions to detect keywords which are in invalid sections
Moved WellInjectionproperties to separate files.
Added CMODE_UNDEFINED enum values
Fixed initialisation of well properties

Previously the control mode was initialized to ORAT; this was later set
to the correct value when parsing the relevant keywords - but in the
case of a SHUT well the control mode was not updated, and we were left
with a well under ORAT control.
Fixed log message
Added extra test case for closing wells.
Merge branch 'wellsmanager-crash' of https://github.com/joakim-hove/opm-parser
Added functionality to calculate PORV property.
Added BoxTest which will throw for oversized keyword
Merge pull request #296 from andlaus/add_section_awareness

Add section awareness
Merge pull request #326 from joakim-hove/wellsmanager-crash

Wellsmanager crash