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

Adding images support for doxygen documentation ( in doc/img ) + automated images generation with graphviz & make

Added class graph, caller and call graph

Now _fields and table MUST be class attribute.
Its important to note that _fields now consist in a list of (name, ftype) tuples and that ftype is a EmFieldType class and NOT an EmFieldType instance