Much cleaner (but incompatible) implementation of subset.neuronlist
update docs for subset.neuronlist - inc fixes of dontrun examples
doc fixes
fix some tests to accommodate new subset.neuronlist prototype
Merge branch 'fix/subset.neuronlist'

* fix/subset.neuronlist:
  fix some tests to accommodate new subset.neuronlist prototype
  doc fixes
  update docs for subset.neuronlist - inc fixes of dontrun examples
  Much cleaner (but incompatible) implementation of subset.neuronlist