Clarified how to test new sample data.
Release step count inlining and documentation improvements.
Release initial header and schema ID schemas.
Updated date names in header schema.
Updated date names in sample data for header and data-point schemas.
Moved effective_time_frame definition to properties only.
Rename start_time to start_date_time and end_time to end_date_time.
Merge branch 'master' into wip