Added get_target_space() to model base class
Added binary_target and target_dim as inputs to softmax, added _target_space as datamember
Changed Softmax cost to use indexing instead of multiplication if the target space is an IndexSpace
Changed DefaultDatasetMixIn to call get_target_space
Actually added target_dim as input
Imported IndexSpace
Added a missing self.
Changed some parameters in 'rbm_tools.py' in order to reduce the running time of 'test_ais.py'.
Added get_target_space to mlp and Composite layer
Changed get_monitor_dataspecs to use target_space, fixed softmax cost to use gpu
Softmax cost is now fixed to account for multidimensional targets
Merged from LISA Labo
Updated get_target_space docstring, cleaned up softmax cost, added binarytargetdim to languagemodel
Changed default value of dinary_target_dim to None from False
Uncommented input in languange_model
From now on, test_ais.py can either be run in fast/innacurate mode or slow/accurate mode.
Made code PEP8 compliant
Fix regression w.r.t. !pkl tag.

Use yaml.serialize(node) rather than 'mapping' in multi_constructor_pkl
for the yaml_src.
Removed trailing whitespace, reduced length of a docstring, split long line of code accross multiple lines
Added regression test for 2ffbb64.