Xbehave 2.0.0-rc003-build581

Learn more about Target Frameworks and .NET Standard.

• • Xbehave.Core (= 2.0.0-rc003-build581)
  • xunit (>= 2.0.0 && < 3.0.0)

### New
* Based on xUnit.net 2.0 and supports all new xUnit.net 2.0 features ([#51](https://github.com/xbehave/xbehave.net/issues/51)).
* `IStepContext` metadata ([#146](https://github.com/xbehave/xbehave.net/issues/146)).
* `OnFailure()` step builder method to control the behavior of remaining steps if the step fails ([#247](https://github.com/xbehave/xbehave.net/issues/247)).
* `StepDefinition` filter attributes ([#254](https://github.com/xbehave/xbehave.net/issues/254)).
* `x()`, an alternative to `f()` and `_()` ([#238](https://github.com/xbehave/xbehave.net/issues/238)).

### Changed
* When a step fails, all following steps in the scenario are reported as skipped. In xBehave.net 1.x, all following steps in the scenario were reported as failed.
* The `Before()` and `After()` methods of a `BeforeAfterTestAttribute` are now called before and after each scenario is run. In xBehave.net 1.x, these methods were called before and after each step within a scenario was run.
* [[Object disposal]] and [[Teardown]] are no longer represented as a separate test unless they fail. This aligns with the behaviour of most xUnit.net 2.0 runners which show an extra failed test when test clean up fails.

### Removed
* `Given()`, `When()`, `Then()`, `And()` and `But()`. Use `f()`, `_()` or `x()` instead.
* [[Timeouts]] have been removed under the same rationale used for [xUnit.net 2.0](https://xunit.github.io/docs/test-migration.html).
* [[Isolated steps]] have been removed as this is a rarely (if ever) used feature that adds considerable implementation overhead.
* [[Object disposal]] without passing a context object to `Using()` (deprecated in 1.x).
* An undocumented feature which allows global continuation of step execution when certain types of step fail.
* An undocumented feature which allows omission of arguments from scenario names in test output.

* rc-003: Added IStepContext metadata, OnFailure and StepDefinition filter attributes
* rc-002: Added Xbehave.Core package
* rc-001: Switched steps following a failed step from failed to skipped, added x(), tweaked messaging behaviour
* beta-008: Fixed NCrunch support and re-introduced BeforeAfterTest support.
* beta-007: Fixed Resharper runner support and removed flawed BeforeAfterTest support.
* beta-006: Fixed VS runner support.
* beta-005: Updated to xunit 2.0.0 (stable) and restricted platform support to .NET 4.5 only.
* beta-004: Fixed test output for steps which are failed fast due to failure of preceding steps.
* beta-003: Fixed test class construction and disposal and changed behaviour of BeforeAfterTestAttribute.
* beta-002: Added support for Windows 8.1+ (Universal), Windows Phone 8 (Silverlight), Windows Phone 8.1+ (Universal).
* beta-001: Initial beta.