[WIP] Implement dict to receive Object as key

[HyeockJinKim]

Implement dict struct that takes Object as key store key and value in array together so that dict is ordered

Issue #118

[codecov-io]

Codecov Report

Merging #119 into master will decrease coverage by 0.65%. The diff coverage is 0%.

@@            Coverage Diff            @@
##           master    #119      +/-   ##
=========================================
- Coverage   72.85%   72.2%   -0.66%     
=========================================
  Files          60      60              
  Lines       11949   12057     +108     
=========================================
  Hits         8706    8706              
- Misses       2709    2815     +106     
- Partials      534     536       +2

Impacted Files	Coverage Δ
py/dict.go	36.65% <0%> (-35.03%)	:arrow_down:

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[HyeockJinKim]

Since Hash is not implemented properly in gpython, I'm going to implement a dict that takes an Object as a key first.

So, even if an object representing the same value comes in as key, the value is not found correctly.

This can break the test code, so instead of getting rid of StringDict, I will fully implement Dict and replace StringDict with Dict.