VIP: Allow raise without reason string

[iamdefinitelyahuman]

Simple Summary

Allow use of raise without a reason string.

Motivation

1. I see no technical reason to enforce requiring a revert string. A bare raise statement is parseable.
2. Requiring a reason for raise but not assert is inconsistent.
3. The requirement is easily circumvented:

assert False

Specification

Fairly self-explanatory. The following syntax should compile:

if cond:
    raise

Backwards Compatibility

Will not cause any issues.

Copyright

Copyright and related rights waived via CC0

[charles-cooper]

I'm on board with this