Official 2.0 release

Fix issue with Date as variable (graphql-dotnet#745)

fixes graphql-dotnet#744

Added Date, DateTime, DateTimeOffset and TimeSpan Scalar Types (graph…

…ql-dotnet#665)

* Use default DateFormatString & IsoDateFormat is already the default.

* Add TimeSpanMillisecondsGraphType & TimeSpanMillisecondsGraphType

* Fix TimeSpanSecondsGraphType serialize

* Fix DateTime to DateTimeOffset conversion

* Add TimeSpanSecondsGraphType and TimeSpanMillisecondsGraphType to GraphTypesLookup

* Fix SchemaPrinterTests tests

* Fix RegisteredInstanceTests tests

* Fix MutationTests

* Fix SchemaIntrospectionTests

* Fix StarWarsIntrospectionTests

* Add TimeSpanMillisecondsGraphTypeTests and fix

* Fix TimeSpanMillisecondsGraphType TimeSpan parsing

* Add DateGraphTypeTests

* Remove skipped test

* Add DateTimeOffsetGraphTypeTests

* Add TimeSpanSecondsGraphTypeTests

* Remove tests no longer needed

graphql-dotnet#529 adding support for IEnumerable type arguments othe…

…r than generic lists (graphql-dotnet#533)

485 - wrap resolve result data

Wrap resolve result value data into dictionary

Fix index issues in MethodModelBinderResolver

* Add ability to include UserContext

Fixes graphql-dotnet#455

Cleanup IValue

Merge pull request graphql-dotnet#439 from graphql-dotnet/issuefixes

2.0 Issue Fixes

Merge pull request graphql-dotnet#434 from graphql-dotnet/bugs/doubles

Another attempt at fixing the decimal number parsing/printing

Fix usage of obsolete method