Jar launcher (Easier scripts maintenance by mutualization)

Launch scripts changes for easier maintenance:
- New "jar_launcher" (.sh & .bat) for common configuration (used to be duplicated from one script to another)
- Re-written simplified scripts using jar_launcher

Sharing a common root script allows easier bugfix propagation, as well as focusing on the essential for every different tool (concerned Launcher, additional possible src-path...).

Scripts tested on Linux, MinGW & Cygwin.

A possible "breaking" change is that we now set the "runtime" source-path entry as the last one after the user-provided arguments ($@ in .sh / %PARAMS% in .bat). This allows replacing the "runtime" files more easily if needed, since user ones will be found earlier in the path. If this point causes any debate or issue, please let us know !

Our other scripts using jar_launcher (as examples):
- Our Mindoc: https://github.com/Mind4SE/mindoc/tree/master/src/assemble/resources
- MindUnit: https://github.com/Mind4SE/mindunit/tree/master/mindunit/src/assemble/resources
- Mind C++ https://github.com/Mind4SE/mind-cpp/tree/master/mindcpp/src/assemble/resources
- Dependency Tools: https://github.com/Mind4SE/dependency-tools/tree/master/src/assemble/resources/bin
- Mind Visual Diff: https://github.com/Mind4SE/mind-visual-diff/tree/master/src/assemble/resources