Move to src/ layout

[tony]

No description provided.

[codecov]

Codecov Report

Merging #414 (03a7a9e) into master (5cd0bfc) will not change coverage.
The diff coverage is n/a.

❗ Current head 03a7a9e differs from pull request most recent head 778ceeb. Consider uploading reports for the commit 778ceeb to get more accurate results

@@           Coverage Diff           @@
##           master     #414   +/-   ##
=======================================
  Coverage   86.22%   86.22%           
=======================================
  Files          21       21           
  Lines        1807     1807           
  Branches      276      276           
=======================================
  Hits         1558     1558           
  Misses        170      170           
  Partials       79       79           

Impacted Files	Coverage Δ
src/libtmux/__about__.py	100.00% <ø> (ø)
src/libtmux/__init__.py	100.00% <ø> (ø)
src/libtmux/common.py	82.27% <ø> (ø)
src/libtmux/conftest.py	84.00% <ø> (ø)
src/libtmux/exc.py	100.00% <ø> (ø)
src/libtmux/formats.py	100.00% <ø> (ø)
src/libtmux/pane.py	78.40% <ø> (ø)
src/libtmux/pytest_plugin.py	78.94% <ø> (ø)
src/libtmux/server.py	72.13% <ø> (ø)
src/libtmux/session.py	75.41% <ø> (ø)
... and 2 more

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