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

- The set_query_filter() method handles subquery creation
- The run isn't written yet...

- separates LeGetQuery tests and LeFilteredQuery tests
- small bugfixes associated to tests

- adds tests on filter parse & check
 - standart filters parse & check
 - relational filters parse & check
- bugfixes related to tests in query.py
- update the example and the test EM
- bugfixes in admin script

Doing so forbids operators like << == =! in* etc..
The tests were updated