Use taxadb for taxonomic data operations

[clnsmth]

Taxonomic data is central to ecocomDP and fast alignment of taxonomic entities with traversal of associated hierarchies are arguably essential.

Currently, there is no built-in support for operations like these in the ecocomDP R package.

taxadb offers a nice solution to all of this, by providing static snapshots of major taxonomic authorities through a consistent API. Note, we may want to implement this as a suggested package.