ParserDoubleItem: Fix typos in exception message
Merge pull request #341 from andlaus/fix_typos_in_error_message

ParserDoubleItem: Fix typos in exception message
Parser: rename the internal parseStream() method to parseState()

there is still the public variant of Parser::parseStream() which
parses an arbitrary std::istream. the name of the state-taking variant
was just confusing, IMO...
ParserState: make it possible to detect if initialization went wrong

this is required to get meaningful error messages if the file
specified by INCLUDE does not exist.
Merge pull request #348 from andlaus/ParserState_improve_construction_failure_detection

ParserState: make it possible to detect if initialization went wrong
ParserKeyword: fix typos and improve exception messages
grid property modifier keywords: make the box specifiers optional for all of them

this means adding defaults to EQUALS and COPY. While at it use -1 as
the default value for boxes in all of these keywords...
EclipseState: make it instantiable without a grid

instead of throwing, we now add a warning to the parser log...