Render SaveCanSAS1D extendable

Make protected methods and chose some methods to be virtual.

re #6839
Introduction of SaveCanSAS1D2.

This algorithm implements the CanSAS version 1.1

re #6839
Add unit test to SaveCanSAS1D2

re #6839
Add LoadCanSAS1D2 the second version

it allows to load cansas version 1.1

re #6839
Merge remote-tracking branch 'origin/feature/6839_cansas_v1.1'