Take namespaces declared locally into account

[andy128k]

Closes #154

[codecov]

Codecov Report

Merging #155 (753b19c) into master (69336ea) will increase coverage by 0.39%.
The diff coverage is 87.30%.

@@            Coverage Diff             @@
##           master     #155      +/-   ##
==========================================
+ Coverage   81.15%   81.54%   +0.39%     
==========================================
  Files          24       24              
  Lines        1528     1539      +11     
==========================================
+ Hits         1240     1255      +15     
+ Misses        288      284       -4     

Files Changed	Coverage Δ
src/channel.rs	88.25% <78.12%> (-0.40%)	⬇️
src/item.rs	95.20% <94.73%> (+3.64%)	⬆️
src/extension/util.rs	86.20% <100.00%> (+1.30%)	⬆️