Calendar mode 'planning' - create placeholder timeslots for future entries, then accept/deny them once completed

[hmerritt]

Would be an awesome feature if

• WHEN in Calendar mode,
• AND you select a slot in the future,
• THEN it creates a placeholder slot, which needs to be accepted/denied before coming a permanent entry

This would add time-planning to Solidtime, which I think would fit very nicely to the existing feature-set