v4.0.0-beta.1

Use typescript based @derbyjs/racer

• Add missing scope for racer 0269bf9
• Use @derbyjs package scope 2962c75
• Use beta @derbyjs scoped racer eb1a5e0
• Fix remaining types e542d37
• Remove generic params for derby classes; Add typedef extending racer types 60fe345
• Use racer-2 branch for racer dep 3bbe67f

v3.0.1...v4.0.0-beta.1