prepare_dataset_species: Read the species for the raw datasource, save them to the...
In inbo/watervogelanalysis: Analysis of the Wintering Birds

Read the species for the raw datasource, save them to the results database

1 2	prepare_dataset_species(raw_repo, result_channel, flemish_channel, walloon_repo, scheme_id, first_date, latest_date)

`raw_repo`	a git_repository object to write the output to
`result_channel`	An open RODBC connection to the results database
`flemish_channel`	a DBI connection to the Flemish database
`walloon_repo`	a git_repository object to the Walloon source data
`scheme_id`	the id of the scheme
`first_date`	earliest records to take into account
`latest_date`	until which date should we import the species list