Update basal_area function for name handling

[GregGuerin]

Update basal_area calculation from $veg.basal table by adding choice to use default herbarium_determination or new standardised name field when added to database.

• current upstream and downstream code must not be broken. Since the output contains the herbarium_determination field when by.spp=TRUE, this must be returned by default

-add a warning to default data return on names with suggestion to run on standardised names