Scab

What's Changed
* Development by briney in https://github.com/briney/scab/pull/6


**Full Changelog**: https://github.com/briney/scab/compare/v0.1.0...v0.2.0

What's Changed
* Development by briney in https://github.com/briney/scab/pull/5


**Full Changelog**: https://github.com/briney/scab/compare/v0.0.6...v0.1.0

Updates
------------
* better defaults for `filter_and_normalize()`
* add an `ignore_ig` option to `dimensionality_reduction()` which ignores immunoglobulin genes during PCA, clustering and UMAP embedding
* added `bar()`, `scatter()` and `umap()` functions to `scab.pl`
* default `obs` field for assignments when using `demultiplex()` was changed to `cellhash_assignment`
* add a `concat()` method to `scab.io` which concatenates multiple `AnnData` objects
* general bugfixes

Major documentation update

minor bugfixes

New features:
- Added a new ``calculate_agbc_confidence()`` function, which builds a probabilistic model of antigen barcode (AgBC) data using a control dataset and assigns confidence values for AgBC positivity.
- Added a new ``qc_metrics()`` plotting function, which produces percent Ig, percent mito, and gene counts plots to assist in determining appropriate threshold values for pre-processing.