Scan top-level imports and create dummy classes

[JSAbrahams]

Relevant issues

First part of #174

Summary

In future we will need a system to get the actual signature of these classes as well. This is a future milestone.

Added Tests

Happy

• parse import
• parse import alias
• parse from import
• parse from import alias

Sad

• parse import with one too many alias

[codecov[bot]]

Codecov Report

Merging #379 (2787519) into develop (63cc218) will increase coverage by 0.01%. The diff coverage is 98.14%.

@@             Coverage Diff             @@
##           develop     #379      +/-   ##
===========================================
+ Coverage    87.00%   87.02%   +0.01%     
===========================================
  Files          109      109              
  Lines        11950    12004      +54     
===========================================
+ Hits         10397    10446      +49     
- Misses        1553     1558       +5     

Impacted Files	Coverage Δ
src/check/context/clss/generic.rs	93.15% <92.30%> (-0.04%)	:arrow_down:
src/check/context/generic.rs	97.36% <100.00%> (+2.13%)	:arrow_up:
src/check/context/mod.rs	95.91% <100.00%> (+1.32%)	:arrow_up:
src/check/context/clss/mod.rs	85.81% <0.00%> (-2.84%)	:arrow_down: