Release v0.15.2

• Added: audformat.Table.map_files()
• Fixed: audformat.Database.load()
  for databases that contain a scheme
  with labels stored in a misc table
  that is using schemes for its columns.
  Before it could fail
  if the schemes were not loaded in the correct order
• Fixed: audformat.Table.drop_index()
  and audformat.MiscTable.drop_index()
  when the provided index to drop
  contains entries
  not present in the index of the table.
  Before it was extending the table
  by those entries
  besides dropping overlapping indices