#225 accidentally added a duplicate .editorconfig to the repo as well as to the solution.
#257 removed the duplicate .editorconfig, but not its entry in the solution.
This update removes the extra .editorconfig reference to a version that #257 already removed from the repo.
To maintain consistent code style between contributors and simplify merging, the solution should provide a .editorconfig to set some basic rules (already used by the current code source).
- use `UTF-8` with BOM (some files are without)
- use CR-LF
- use <kbd>Space</kbd> to indent (sorry #teamTab)
- trim trailing whitespace
- be sure to add a new line at the end of files.
[Documentation](https://docs.microsoft.com/en-us/visualstudio/ide/create-portable-custom-editor-options?view=vs-2017)
