Session snapshot with filters, charts, bookmarks and comments

[DmitryAstafyev]

We have some users who are interested in exporting/importing session states into the file (#1648).

Requirements

• such kind of import/export would be possible for sources, where we have a checksum available. That means - for files only
• We would not change the way we manage presets: import/export filters should stay like it is. Actually, we are talking about a snapshot of the session state binding to the file.

Possible workflow

• collected all session data: filters, charts, bookmarks, comments
• get checksum of opened file
• export data into the file

Comments

• correctly comments features are available only via the teamwork feature
• probably makes sense to allow it in local mode. But in this case, we must always make a snapshot of the session automatically in the background.