Circular call logic and exception annotations

[iamdefinitelyahuman]

Fixes: #1707

What I did

• allow exceptions to be annotated with multiple nodes
• add circular call check
• check for modificaiton of iterated array in for loop, including via function calls
• misc fixes to interfaces and events

Sooooo close....

How to verify it

Run tests. Read code.

Cute Animal Picture

[fubuloubu]

This solves #1707 right?

[iamdefinitelyahuman]

This solves #1707 right?

Yes :)))

[codecov-commenter]

Codecov Report

Merging #2028 into next will decrease coverage by 0.00%.
The diff coverage is 89.52%.

@@            Coverage Diff             @@
##             next    #2028      +/-   ##
==========================================
- Coverage   85.09%   85.08%   -0.01%     
==========================================
  Files          83       83              
  Lines        7982     8051      +69     
  Branches     1925     1951      +26     
==========================================
+ Hits         6792     6850      +58     
- Misses        716      721       +5     
- Partials      474      480       +6     

Impacted Files	Coverage Δ
vyper/signatures/event_signature.py	77.61% <0.00%> (-2.99%)	⬇️
vyper/context/validation/module.py	89.04% <87.17%> (-0.78%)	⬇️
vyper/exceptions.py	97.87% <91.66%> (+2.36%)	⬆️
vyper/context/validation/local.py	91.28% <92.59%> (-0.22%)	⬇️
vyper/context/types/event.py	94.28% <100.00%> (+0.34%)	⬆️
vyper/context/types/function.py	86.40% <100.00%> (+0.22%)	⬆️
vyper/context/types/indexable/sequence.py	84.00% <100.00%> (ø)
vyper/context/types/meta/interface.py	88.31% <100.00%> (+0.64%)	⬆️
vyper/parser/stmt.py	79.46% <100.00%> (ø)
vyper/parser/parser.py	86.81% <0.00%> (-2.20%)	⬇️
... and 2 more

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