Refactor clipboard exporter as a function

[cydanil]

Description

This simplifies the clipboard exporter to a single function, rather than an object.

Ingredients that do not have quantities are now better formatted, as mentionned in #26 , as well as links if any.

How Has This Been Tested?

This was tested by updating the test, and by copying a recipe to a text file and checking the expected output.

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.

[lgtm-com]

This pull request introduces 1 alert when merging a12aff9 into d2df803 - view on LGTM.com

new alerts:

• 1 for Unused import