Commandline usage: Set project directory

[jjvbsag]

(This may be related to #829 but I'm adding a separate issue, because the use case is a different one)

I'd like to start zbstudio from commandline and pass a directory to be used as project directory, e.g. zbstudio projects/project1.
Especially I'd like to have zbstudio to understand the command zbstudio . to start and set the project directory to the current working directory of the command shell.

[jjvbsag]

Ok, closing this, as it will be resolved, when #829 is fixed.