Refactor thumbnail generation

Break thumbnail generation into handful of functions
Fix one level deep image thumbnails
Rename variables for clarity
Redefine thumbnail retrieval

Remove dynamic URL thumbnails
Change to always silently cache
Remove dumb settings
Clean up default theme
Break out filesystem functions into own object
Fix caching functionality

Fully implement optional descriptions
Finish overhaul

Finish documentation
Make theme responsive
Switch to sample photos from personal collection
Rejigger initialization
Make into composer package