Updating the Gherkin Parser

Under the hood SpecFlow uses the parser of the Gherkin project for parsing feature files.

The Gherkin project publishes a .NET dll of the parser as part of their release process.

Some steps are necessary to import this dll into the SpecFlow project. This is the process:

0. compile SpecFlow
1. download gherkin-x.y.z.dll from gherkin github to lib\gherkin
2. in a command prompt, go to: Installer\ImportGherkinParser\bin\Debug
3. run import.cmd gherkin-x.y.z.dll
4. run all the SpecFlow tests
5. remove the old gherkin dll from lib\gherkin
6. update changelog