New/Switch project decisions

[imnasnainaec]

Follow-up to #85, decisions to make:

• When an interlinear project is selected and user creates a new project, will they have a choice to duplicate the current project vs start from blank?
• When no interlinear project (but some analysis has been done) and user creates a new project, will their work automatically be added to the new project (rather than being lost)?
• If user has only one interlinear project, do we want to auto-select it when interlinearizer loads?
• If user has multiple interlinear projects, do we want to track the most recent so that we can load it when interlinearizer loads?

[imnasnainaec]

Decisions:

• Try to not have a gate, but automatically create an interlinear project, in which they can change the options as needed
• Track the user's most recent project, and open automatically if that is their only project
• If there is a project other than the user's most recent, gate for them to select a project
• When creating a new project, it should be a blank project (we'll only allow creating a duplicate later if requested)