create_participant_table: baseline timing EPOCH == BASELINE then VISITDY == 1, change from any of VISITDY == 1, DY == 1 and EPOCH == BASELINE
prepare_domain: data first, domain second in parameter order to align with tidy principles, changes to downstream functions, examples, documentation, tests and vignette
prepare_domain: added a print message describing the timing variables used in console
table_variables: data first, domain second in parameter order to align with tidy principles