Support decompress of archive with COPY method

[miurahr]

COPY method is defined to use make 7-zip archive from 7-zip or zip archive to avoid a duplicated compression.

[miurahr]

Need to fix lint error

[codecov]

Codecov Report

Merging #61 into master will decrease coverage by 0.04%.
The diff coverage is 78.33%.

@@            Coverage Diff             @@
##           master      #61      +/-   ##
==========================================
- Coverage   83.71%   83.67%   -0.05%     
==========================================
  Files           8        8              
  Lines        2156     2169      +13     
  Branches      352      352              
==========================================
+ Hits         1805     1815      +10     
- Misses        225      228       +3     
  Partials      126      126

Flag	Coverage Δ
#linux	82.75% <78.33%> (-0.04%)	⬇️
#mac	82.57% <78.33%> (-0.04%)	⬇️
#py35	79.32% <78.33%> (-0.02%)	⬇️
#py36	83.34% <78.33%> (-0.04%)	⬇️
#py37	83.34% <78.33%> (-0.04%)	⬇️
#py38	83.47% <78.33%> (-0.04%)	⬇️
#windows	82.43% <78.33%> (-0.04%)	⬇️

Impacted Files	Coverage Δ
py7zr/compression.py	79.81% <78.33%> (+0.5%)	⬆️
py7zr/archiveinfo.py	83.17% <0%> (-0.24%)	⬇️

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