This PR tries to use the mappings from MRREL to supplement the information from MRCONSO in mapping from one vocabulary to another. There any many relations in MRREL, and this PR provides methods for accessing them. However, it appears that all the hierarchy information obtained from MRREL was already present in the MRHIER table we were using earlier. Therefore, I'm going to put this PR on hiatus until we actually need to tap into the MRREL information.
This PR tries to use the mappings from MRREL to supplement the information from MRCONSO in mapping from one vocabulary to another. There any many relations in MRREL, and this PR provides methods for accessing them. However, it appears that all the hierarchy information obtained from MRREL was already present in the MRHIER table we were using earlier. Therefore, I'm going to put this PR on hiatus until we actually need to tap into the MRREL information.
Should be merged after #5.