Implement more tests and functionality

[jerbob92]

Add even more tests and implement:

• create_inheriting_constructor
• emval_equals
• emval_strictly_equals
• emval_set_property and emval_get_property for slices and maps

[codecov-commenter]

Codecov Report

Merging #5 (4e4a3a5) into main (0038b1c) will decrease coverage by 0.02%.
Report is 2 commits behind head on main.
The diff coverage is 64.70%.

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@@            Coverage Diff             @@
##             main       #5      +/-   ##
==========================================
- Coverage   72.47%   72.46%   -0.02%     
==========================================
  Files          21       21              
  Lines        4491     4667     +176     
==========================================
+ Hits         3255     3382     +127     
- Misses        876      905      +29     
- Partials      360      380      +20     

Files	Coverage Δ
internal/engine.go	70.80% <50.00%> (-0.88%)	⬇️
internal/class.go	78.31% <71.83%> (-0.33%)	⬇️
internal/emval.go	60.50% <62.66%> (+0.78%)	⬆️

... and 1 file with indirect coverage changes