Added option to allow the user to make the contributions listing dependent on the PDE version

This fixes [#2581](https://github.com/processing/processing/issues/2581).

This would require a new field in the contributions.txt and the .properties files. The field would consist of a comma separated list of integers, separated by dashes (-) for ranges. If the last entity has the right side of its - without a number, it implies that the contribution is compatible with all revisions of Processing after that number (including the number itself). For an example, refer the documentation [here](https://github.com/joelmoniz/processing/compare/compatibleContribs#diff-74478d61b7d969b43a82b5c67a4cbf27R241).