A description of the output file formats is added to the documentation.
In particular, the outline of JSON headers for projector-group (*.plog<Ng>)
and control (*.ctrl) files are given.
The documentation has been slightly rewritten and extended to follow
the recent changes. The modifications include:
- ProjectorSet class is now replaced by ProjectorShell
- the workflow has been refined
- the electronic structure part is represented by class ElectronicStructure
