Take address of complex expressions. Fixes #715

[kamphaus]

Fixes #715

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This change is 

[codecov]

Codecov Report

Merging #716 into master will increase coverage by 0.03%.
The diff coverage is 95.12%.

@@            Coverage Diff             @@
##           master     #716      +/-   ##
==========================================
+ Coverage   82.03%   82.07%   +0.03%     
==========================================
  Files         164      164              
  Lines        9057     9086      +29     
==========================================
+ Hits         7430     7457      +27     
- Misses       1223     1224       +1     
- Partials      404      405       +1

Impacted Files	Coverage Δ
transpiler/operators.go	78.4% <100%> (+0.38%)	⬆️
util/goast.go	88.71% <93.33%> (+0.06%)	⬆️

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[elliotchance]

Reviewed 2 of 3 files at r1, 1 of 1 files at r2.
Review status: all files reviewed at latest revision, all discussions resolved.

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