Initial release

This is the initial release of the MIMIC IV to OMOP conversion.
This release matches the OMOP CDM compiled from MIMIC IV demo data provided to the PhysioNet platform for publication of the project MIMIC data in OMOP Common Data Model (Demo).
It contains conversion logic for the modules core, hosp and icu.
The main v1.0 release will also contain additional documentation such as the specifications document and some test guidance.