Remove/deprecate old stryker options

[nicojs]

We should remove or deprecate the stryker options that v4 no longer uses. A (maybe non-extensive) list:

• transpilers
• mutator.name
• Defining mutator as string
• testFramework

We should remove these, or log a warning when people use them. Maybe we can give a comprehensive error message pointing people to the blog article (that needs to be written).

[bartekleon]

@nicojs I think as long as we update schema and people would actually use it, they will know that they cant use these options anymore (thats for "log a warning when people use them")

[nicojs]

Yeah, true. But that might be a unfriendly message. I was thinking to write a custom message with a link to a future blog article or migration guide thing