Sat Apr 12 11:37:27 CEST 2014  Emmanuel Garette <egarette@cadoles.com>

	* behavior change in master/slave part of code:
	if slave has a default value greater than master's one, it's raise
	SlaveError, didn't try to reduce the slave's length
	* tiramisu/config.py (in cfgimpl_get_home_by_path and getattr) and
	tiramisu/value.py (in getitem): arity change, remove force_properties
	* tiramisu/option.py: split into tiramisu/option directory
	* tiramisu/option/masterslave.py: master/slaves have no a special
	object MasterSlaves for all code related to master/slaves options
	* tiramisu/option/masterslave.py: master and slaves values (length,
	consistency, ...) are now check every time
	* change None to undefined when needed