Making progress on new PhotosDB engine for osxphotos

[RhetTbull]

For a while I've been working on a new database engine for osxphotos for working with the Photos database. The current design loads the entire Photos database into python data structures before working with it. In practice this means simpler internals (minimize SQL queries throughout the code) and fast property access but it also means slow startup (15-20 seconds on my M4 for a 40k image library) and very high memory usage. The new engine accesses data from the database only when it's needed using optimized queries and doesn't keep data in memory longer than needed. There's still a fair bit of work to go before I can refactor this into osxphotos but as an example, here's a comparison of osxphotos info on my 40k asset library on my M4 MBP. The new version is 10x faster and uses 10x less memory.

osxphotos info

current: 14.72 seconds
new:     1.67 seconds
current: 1879885840 RAM usage
new:     176013864  RAM usage

[RhetTbull]

The new version is also thread safe and can support multiple threads querying the database which should open up parallel export.