Improved README info on install options
fix warning when installing from zip file

* normalizePath only when zip actually exists on disk
* and error out it isn't there!
normalising zip path in download_zip is not required

* and complicates testing
* also make download test more forgiving
Teach install_analysis_suite to check for existing AnalysisSuite directory
docs
Add is_analysis_suite_installed()
Use is_analysis_suite_installed in new .onAttach hook

* thereby silencing one more CRAN note since .packageStartupMessages
  are preferred in .onAttach rather than .onLoad
move neuron and neuronlist documentation to nat

* these should obviously be some of the first things that I add to nat package
README polishing
remove neuron*.Rd files as well
Prepare 0.4.1 release
Add nat.utils, rgl, RANN and igraph as dependencies

* this means that they will be attached (if nat.as is attached)
* and that they will be installed if required
fix test - was failing on windows due to path ambiguities

* seems that one really has to normalise the supplied
  and returned path to ensure they point to the same thing
Bump version to 0.5