Evaluate if it possible to split classes shared with Netdroid

[masesdevelopers]

Two options were identified:

* **submodule**:

  * link JNet repository with a submodule
  * remove copied classes and link them to the submodule folder
  * for JVM side the best way is to create symlinks otherwise, from current knowledge, Maven is not able to compile classes outside pom.xml subfolders

The previous option in any case do not guarantee that changes on JNet side are completely available because, in case of new classes, the Netdroid project shall be reviewed to check if something is missing.

* **request a change to JNet**: maybe JNet project, instead to have all classes in the same folder, can create different folders
  
  * one, ore more, folders with the common classes: containing, at least, the classes JNetReflector expects to be available
  * other folders with remaining classes specific to the project

The previous needs a request to be opened on JNet project.

Originally posted by @masesdevelopers in masesgroup/netdroid#76 (comment)