Now the _LeObject.get() method should be able to return LeType child classes instance
LeType has two new methods :
	- LeTypes.datas() @property method that returns a dict(FIELDNAME:FIELDVALUE)
	- LeType.populate() that fetch from datassource missing fieldvalues

An old string was given as argument to DummyMigrationHandler and was interpreted as debug = True

Added a test on LeFactory generated code

Associated tests has been added/updated

Update the associated tests

Methods are _LeObject.get() and LeType.check_datas()

Now on load default fields for EmClass are created. The EmClass.check method create them if they are not present.

Checking that internal='object' is reserved for common fields

This method split a string in a tuple(FIELD, OPERATOR, VALUE)

Added default fields for EmClass, they are listed by classtype in EmClassType
Fixing some tests (testing that a new EmClass has no fieldgroups)
Fixing the delete_check of EmClass. Now an EmClass can be deleted if it contains only default fieldgroup and default fields

This commit is in "work in progress state" all the code is not consistent

LeFactory.generatePython() is a method that generate LeObject code and python classes for each EmClass and EmType in an EditorialModel

Add a check for the default value
Removed the _fieldtype_instance attribute

Now fieldtypes are not derivated from EmField anymore