Resolve real path to the executable

[nohal]

The run.sh scripts assumes it is in the current working directory and fails to actually start the bin/cq-editor binary if it is not so, making the $HOME/cq-editor/run.sh suggested as the start command in https://cadquery.readthedocs.io/en/latest/installation.html#adding-a-nicer-gui-via-cq-editor fail.

Resolving the actual location of the script and using it to start the binary fixes the problem.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.20%. Comparing base (ffdcc3e) to head (23fd09f).
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #505   +/-   ##
=======================================
  Coverage   88.20%   88.20%           
=======================================
  Files          20       20           
  Lines        1712     1712           
  Branches      182      182           
=======================================
  Hits         1510     1510           
  Misses        163      163           
  Partials       39       39           

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[jmwright]

Thanks @nohal !