refactor: use Rc<RefCell> for pltype

[Chronostasys]

1

[codecov]

Codecov Report

Merging #104 (7f01469) into master (408e517) will decrease coverage by 0.00%.
The diff coverage is 94.06%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #104      +/-   ##
==========================================
- Coverage   87.18%   87.18%   -0.01%     
==========================================
  Files          50       50              
  Lines        5519     5549      +30     
  Branches     5519     5549      +30     
==========================================
+ Hits         4812     4838      +26     
- Misses        707      711       +4     

Impacted Files	Coverage Δ
src/ast/tokens.rs	44.00% <ø> (ø)
src/ast/node/pointer.rs	90.47% <83.33%> (-1.84%)	⬇️
src/ast/node/operator.rs	82.75% <88.88%> (+0.45%)	⬆️
src/ast/node/types.rs	94.27% <88.88%> (+0.44%)	⬆️
src/ast/node/primary.rs	90.00% <90.00%> (-0.13%)	⬇️
src/ast/ctx.rs	80.75% <93.40%> (-0.57%)	⬇️
src/ast/gcapi.rs	98.55% <100.00%> (+0.08%)	⬆️
src/ast/node/control.rs	95.52% <100.00%> (ø)
src/ast/node/function.rs	93.04% <100.00%> (+1.18%)	⬆️
src/ast/node/global.rs	96.00% <100.00%> (ø)
... and 15 more