Add language-level config

[chaemon]

configを言語別に設定できるようにしました。Nimだけに適用されるcodestyleを設定したい場合は[codestyle.nim]等でできます。

また、configのうち、compile_before_testing, compile_only_when_diff_detectedをetc_configから、tester_configに移動しました。

さらに、compilerの説明を追加しました。

[codecov-commenter]

Codecov Report

Merging #233 (fea6203) into stable (67215fe) will decrease coverage by 0.36%.
The diff coverage is 89.68%.

@@            Coverage Diff             @@
##           stable     #233      +/-   ##
==========================================
- Coverage   89.56%   89.20%   -0.37%     
==========================================
  Files          54       58       +4     
  Lines        2780     2519     -261     
==========================================
- Hits         2490     2247     -243     
+ Misses        290      272      -18     

Impacted Files	Coverage Δ
atcodertools/atcoder_tools.py	0.00% <0.00%> (ø)
atcodertools/config/etc_config.py	100.00% <ø> (ø)
atcodertools/executils/run_program.py	83.33% <ø> (ø)
atcodertools/tools/submit.py	53.84% <0.00%> (-4.49%)	⬇️
atcodertools/tools/compiler.py	74.35% <74.35%> (ø)
atcodertools/tools/tester.py	85.58% <82.19%> (-0.06%)	⬇️
atcodertools/common/language.py	94.91% <92.00%> (-2.31%)	⬇️
...odegen/code_generators/universal_code_generator.py	95.79% <95.79%> (ø)
atcodertools/codegen/code_generators/cpp.py	100.00% <100.00%> (+3.70%)	⬆️
atcodertools/codegen/code_generators/cs.py	100.00% <100.00%> (+4.67%)	⬆️
... and 18 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update ef4682c...fea6203. Read the comment docs.

[kyuridenamida]

よさそうっす!