First stab at defining fast load, test stub. Structure bits currently superfluous?
Patched in a temporary working version of prototype collate code.
Reworking FieldGroup --> FieldCollation, integrate into fast_load_structured_fields.
Rearrange testing.
Add collation function test.
Neater test style.
Simple tests working on FieldCollation.
Polish tests + expand.
Factored out the array structure calculation.
Added element priority.  Enhanced joint testing (for now).
Reorganise folders.
tiny tweaks
Fix header date problem.