2.0.0

CalcUS version 2.0.0

This is a major release and is incompatible with the database of CalcUS version 1.

Summary of changes

• Output files are no longer stored on disk in a "results" directory. Instead, they are stored in the database. The scratch directories are still used and will contain the output files until deleted.
• The different objects use a hash ID instead of the ID directly.
• Accounts are uniquely identified by emails instead of usernames. The full name can be specified, but is not required.
• CalcUS can be launched in cloud mode. This mode is suited to hosting on the Google Cloud Platform and using cloud computing resources. The computation time used is "billed" to user accounts. The cloud mode is in a very early stage - use at your own risk.
• The types of calculations allowed and the maximal number of atoms in the input structures can now be specified, both in the cloud mode and in the default mode.
• A large number of bugs have been fixed.

Thanks to @div-yam for fixing some bugs and for implementing the foundations of multi-step calculation protocols. This new feature will be enabled when stable.