getting start on docs for the layers module
refactor ConcatLayer, move concatenation logic into nntools.utils + docs + test
add helper methods to get/set parameter values
Merge branch 'start_docs'
relative imports
more docstrings for the helper functions in nntools/layers/base.py
value() -> get_value()

bugfix
Merge pull request #54 from 317070/patch-1

value() -> get_value()
Turn docstrings added in 00e2865 into doctests.
Merge pull request #55 from dnouri/add-doctests

Turn docstrings added in 00e2865 into doctests.
Allow layers.get_all_layers (and related functions) to work on lists of layers instead of single layers
Merge pull request #61 from f0k/gather-from-many-layers

Support networks of multiple output layers in get_all_layers
Added layers.EltSumLayer
Added test for EltSumLayer
Renamed EltSumLayer (the cuda-convnet name) to ElemwiseSumLayer (a more Theano-like name)
Merge pull request #62 from f0k/eltsumlayer

Weighted elementwise sum layer
Allow handing an existing input variable to InputLayer
Merge pull request #63 from f0k/custom-input-var

Allow handing an existing input variable to InputLayer
Removed a redundant typecast in DropoutLayer
Merge pull request #65 from f0k/drop-dropout-typecast

Removed a redundant typecast in DropoutLayer