Config short

[phlptp]

If merged this PR will allow short only and positional only options to be configurable and output to config files.
The order of preference for output is
first long option, first short option, positional, any form is used on input.

Closes #440

[codecov]

Codecov Report

Merging #443 into master will not change coverage by %.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master      #443   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           12        12           
  Lines         3583      3602   +19     
=========================================
+ Hits          3583      3602   +19     

Impacted Files	Coverage Δ
include/CLI/App.hpp	100.00% <100.00%> (ø)
include/CLI/Config.hpp	100.00% <100.00%> (ø)
include/CLI/Option.hpp	100.00% <100.00%> (ø)

---

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 967bfe0...88cdf65. Read the comment docs.