new entry in the menu : download DipyDocs available for demonstration
added several files linked to the 'demo download', especially qt/downloaddemodipydocs.*
the DownloadDemoDipydocs class can now download and install the demonstration DipyDocs
DownloadDemoDipydocs functions remove old demo dipydocs before installing the new ones
cleaned up DownloadDemoDipydocs class; added error messages
DownloadDemoDipyDocs methods use the DownloadDemoDipydocs::readyRead() signal to consume less RAM in writing the downloaded files
when the demo dipydocs are downloaded, the Open menu is now updated
downloaddemodipydocs.* : cpplint ok
Merge branch 'feature54' into dev
DownloadDemoDipydocs class : download and remove demonstration DipyDocs.