Merge pull request #1 from openalea/master

Update from original
fixing setup in openalea.core
Update README.md
Merge pull request #105 from cokelaer/master

fixing setup to make sub-packages available
Fix #107
Merge pull request #111 from gbaty/fix_107

Fix #107
First draft to restore loader/saver approach.
Apply it to controls and part of Project
Project now use ProjectLoader for loading
All applet plugin follow standard plugin convention: __call__ return applet class.
To add widget in mainwindow and fill menus, just call "graft(oa_mainwindow=maiwnin)" method.

Move oalab.plugins interfaces to core.plugin
Real oalab plugins like applets, paradigms, remain in oalab.plugins
Add a splitable widget that tries to mimic the Blender UI.
All applet plugin follow standard plugin convention: __call__ return applet class.
To add widget in mainwindow and fill menus, just call "graft(mainwindow)" method.
Improve PluginManager.instances, get_applets
Move oalab.plugins interfaces to core.plugin
Real oalab plugins like applets, paradigms, remain in oalab.plugins
First draft to create a GUI inspired by Blender 3D GUI
Add applet icons
Move all plugins linked to plantgl in plantlab
Blender ui become a module instead of simple script
Fix --debug-plugins command line
First draft to migrate OpenAleaLab MainWindow to SplittableUi
Improve and simplify PanedMenu
Add global menu
Fix minor bugs and improve PluginInstanceManger error messages