FIX/CLN: remove unsupported power_expression

[klauer]

Closes #75

[codecov-commenter]

Codecov Report

Merging #76 (a522ef5) into master (11d5c30) will increase coverage by 0.2%.
The diff coverage is n/a.

Additional details and impacted files

@@           Coverage Diff            @@
##           master     #76     +/-   ##
========================================
+ Coverage    78.1%   78.3%   +0.2%     
========================================
  Files          26      26             
  Lines        5339    5339             
========================================
+ Hits         4171    4184     +13     
+ Misses       1168    1155     -13     

Impacted Files	Coverage Δ
blark/tests/test_transformer.py	93.1% <ø> (ø)
blark/transform.py	98.9% <ø> (ø)

... and 2 files with indirect coverage changes

[engineerjoe440]

Looks good! I hadn't even stumbled across this in context of any real 61131. I do agree that this is a good fix! 😄