Add colors module and docs for printing and terminating.

[tiangolo]

📝 ✨ Add colors module and docs for printing and terminating, including tests.

[codecov-io]

Codecov Report

Merging #20 into master will increase coverage by 0.17%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #20      +/-   ##
==========================================
+ Coverage   96.75%   96.92%   +0.17%     
==========================================
  Files          89       96       +7     
  Lines        1817     1921     +104     
==========================================
+ Hits         1758     1862     +104     
  Misses         59       59

Impacted Files	Coverage Δ
docs/src/terminating/tutorial003.py	100% <100%> (ø)
docs/src/terminating/tutorial001.py	100% <100%> (ø)
typer/colors.py	100% <100%> (ø)
...test_tutorial/test_terminating/test_tutorial002.py	100% <100%> (ø)
...test_tutorial/test_terminating/test_tutorial003.py	100% <100%> (ø)
...test_tutorial/test_terminating/test_tutorial001.py	100% <100%> (ø)
docs/src/terminating/tutorial002.py	100% <100%> (ø)
... and 4 more

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