New gradle setup does not play nicely with Intellij

[vanitasvitae]

Hey, as outlined in my comment on https://github.com/bcgit/bc-java/commit/05594043c82ab45bf3b12a5cf5e86a584b83f888 the new gradle setup causes hurdles for development using Intellij.

Intellij complains about a duplicate content root for the pg module. If I manually set back pg/src/main/java as content root, there are dependency issues resolving core.prov. If instead I mark generated-src as content root, Intellij keeps opening the generated source files when I want to make changes, which are then obviously overwritten as soon as gradle re-generates those files from the true sources.

Currently, these changes unfortunately make it very hard to work on BC :/ If you have any tips for me on how to resolve this, apart from basing my branches onto commits before the change, let me know!