Fixes #302 (Setting attributes fails for Projections where either the pre- or post-synaptic Population has size 1)
test: set() fails for (n,1)/(1,n)-shaped arrays
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.