Pre-existing data is not accounted for

[RobMor]

We can skip over some API querying if we first check what data already exists.

• Abstract table creation away from data sources
• Develop mechanism to search for and recognize gaps in the data
• Allow passing of multiple disjoint intervals into data sources
• Change tables in database to prefer newer data (INSERT OR REPLACE)
• Add option for user to force re-collection of all data (-f)