InstData Import/GMT Picard: add downsample ratio mixin
Whitespace.
Allow access to the additional columns that were found.
Whitespace.
Rename "ignore_extra_columns" to "allow_extra_columns".

We're not just ignoring them any more!
spelling: preceed* => preced*
Create add_ methods for links to profile items and subject mappings.
Add support for setting tags when creating subject mappings.
Consolidate get() attempts to single statement.
Set is_mutable so can add_tag() to these.
CQID respects tags set on mappings when deciding what models to create.
class to generate directory of vcf symlinks for data transfer
sanitize file names and clean up some of the variable names.
Update docs.
update docs per @tmooney
punctuation!!!
update object comparison per @tmooney. We cannot trust to get numeric values back on all UR objects.
More doc updates since my grammar was no good.
add a new property downsample_ratio for imported instrument_data
better error handling around missing files