Simple option to use plyr to give progress bars/parallelisation
import plyr

* was thinking of suggesting but then doc links don't work and I think that I might make
  this behaviour the default very soon.
fix doc link
Examples of using plyr/parallel
tests: don't leave pdf lying around

* this happens when running in non-interactive mode with rstudio's build/test
Give cmtk.statistics Verbose argument (default F)
teach read.neuron(s) to read neuronlists

* closes #153
Merge branch 'feature/plyr'

* feature/plyr:
  Examples of using plyr/parallel
  fix doc link
  import plyr
  Simple option to use plyr to give progress bars/parallelisation
c.neuronlist uses rbind.fill to handle missing cols
rbind.fill does not conserve attributes

* but have opted not to test for these since they do not make much sense
  when data.frames are joined together
test: error for duplicate neuron names
fix typo in constructing selected_cols

* also test for columns="matching", which fails because the columns argument ends up
  getting passed to c.default as one of things that it joins together.
* Somehow need to stop NextMethod from passing it on but I can't find any docs about
  removing arguments, only adding arguments
remove columns argument

* It was a nice idea, but not sufficiently useful to warrant debugging the
  NextMethod call which always inherited the columns argument (and therefore
  combined it as the last element of the new list)
Fix joining neuronlists +/- data.frames

* need to make dummy data.frame(s) when some neuronlists have them and some do not
Merge branch 'feature/c.neuronlist-dfs'

* feature/c.neuronlist-dfs:
  Fix joining neuronlists +/- data.frames
  remove columns argument
  fix typo in constructing selected_cols
  test: error for duplicate neuron names
  rbind.fill does not conserve attributes
  c.neuronlist uses rbind.fill to handle missing cols
Always uses plyr::llply in nlapply

* and add improved documentation that reflects this
Bump version to 1.5.12