move lpy dependencies into plantlab
restore picklable curves remove by mistake
lpy model has a default input
fix error with name inside prepare_inputs
remove unused part in test
Move loader and saver (plantgl dependent AND unused) in legacy.
Fix setup.py s.
Move lpy controls into plantlab.
Merge pull request #77 from jucoste/rm_lpy_dependencies_oalab

Remove dependencies to lpy into core and oalab