VIP: rename enum to flags

[charles-cooper]

Simple Summary

per title

Motivation

enum has been a bit confusing, since vyper's enum really follows https://docs.python.org/3/library/enum.html#enum.IntFlag semantics. rename to flags.

Specification

deprecate the enum keyword in 0.4.0, and support it as flags

optionally, introduce a non-flags enum type in 0.5.x series

Backwards Compatibility

All VIPs that introduce backwards incompatibilities must include a section describing these incompatibilities and their severity. The VIP must explain how the author proposes to deal with these incompatibilities.

Dependencies

If this VIP depends on any other VIPs being implemented, please mention them.

References

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Copyright

Copyright and related rights waived via CC0

[ControlCplusControlV]

Will attempt to impl this and make a draft PR

[AlbertoCentonze]

Hey @ControlCplusControlV do you mind if I take over this?

[ControlCplusControlV]

Sure, go ahead!

[charles-cooper]

implemented in #3697