Data files should be in one folder to avoid multiple copies

[dilawar]

Currently each example has its own data file in its own folder. This causes lot of problem when packaging due to duplicate file warnings.

Ideally all data files should be kept in one place and let the examples read them from here.

[dilawar]

There is not much to be gained. Tried with tools called rdfind; at most 1 MB. We have removed large files from repo anyway. They are still in history though. #43