Support for loading configs with periods in directories

[tony]

Fixes #212 #201

[codecov]

Codecov Report

Merging #637 into master will increase coverage by 0.07%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #637      +/-   ##
==========================================
+ Coverage   78.16%   78.24%   +0.07%     
==========================================
  Files           6        6              
  Lines         829      832       +3     
  Branches      239      239              
==========================================
+ Hits          648      651       +3     
  Misses        121      121              
  Partials       60       60              

Impacted Files	Coverage Δ
tmuxp/cli.py	68.55% <100.00%> (+0.26%)	⬆️

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