Hook names were wrong

Test passes

Now backref seems to work at creation of a Person linked with a text the Person UID is appended to Text.linked_persons

The dedup mechanism was using a cast of list to set. But sometimes, filters contains list, and list are not hashable...

- calling check_data_value on filters value to ensure value casting

- Add an update feature to create_instance.sh script
- Updated webui plugin load instruction (running loader.start() in run)
- Updated the way EmCmponents handles EmGroup
- Updated the way EmFields handles EmClass
- Updated xmlfile translator according to EmComponent modification

- Changed the way of instanciating results object in get (using __new__ )

- The LeUpdateQuery implementation is broken or at least have huge performance issue
- Moved LeObject exceptions and LeQuery exceptions in lodel.leapi.exceptions

- Now delete & update methods use filters & rel_filters

- deleting most of **datas to replace it with a standart dict argument
- using filters in childs of LeFilteredQuery

- Added missing allowed_classes options to some references in em_test

- Modified again the em_test to fit with testing purpose
- First test on multi datasource query written
- debugging of query.py

- adding an EmClass to make a double link between indexes and texts
- adding subqueries infos to dump_infos method of LeFilteredQuery