Feature/smoother migration to 2 3 0

[RoyTheunissen]

• Migrating from a version before 2.3.0 to 2.3.0 or newer no longer results in compile errors when you generate static access:
• Fixed generated static access code overwriting the collection definition
• Pre 2.3.0 collections will now be assumed to want a namespace setting that is the same namespace as its item type
• When generating static/indirect access code using the new .g.cs suffix, existing static/indirect access code that uses the old .cs suffix is now automatically removed to prevent compile errors