nest: Fixed handling of inhibitory weights.
First attempt at standardisation of names and parameter names for random distributions (relates to issues #282 and #296).
Forgot to add these files to last commit.
Changed random distribution parameters to kwargs.
Restored the option to specify parameters of random distributions as a tuple (as an alternative to the new option of specifying them as keyword arguments).

Also: added a maximum number of redraws for clipped distributions, updated the documentation.
Merge pull request #300 from obreitwi/nest_projection_weights

nest: Fixed handling of inhibitory weights for conductance-based synapses.
Fixes #302 (Setting attributes fails for Projections where either the pre- or post-synaptic Population has size 1)
Added more comments in connectors.py
test: set() fails for (n,1)/(1,n)-shaped arrays
Incorrect parameterisation of RandomDistributions is now detected at creation time.
Fixed some unit tests broken by previous commit.
Merge pull request #301 from apdavison/standard_random

Standardization of random distributions
Merge branch 'master' of https://github.com/NeuralEnsemble/PyNN

Conflicts:
	src/connectors.py
test: .set() fails for populations
Merge pull request #303 from apdavison/issue302

Fixes #302 (Setting attributes fails for Projections where either the pre- or post-synaptic Population has size 1)
Re-added comments in connectors.py that were lost in merge.
Implemented/fixed `FixedNumberPreConnector`. Fixes #295.
Fix `nest.Projections._convergent_connect()` to handle creation of multiple connections to a single pre-synaptic neuron.
Fix (?) an issue when creating multiple connections to a given pre-synaptic cell, with dynamic synapses.
added grng_seed to the modifiable parameters of NEST via pyNN.nest.setup()