tiny-plot: inclusive/exclusive filters for classes in DGE scatter plots

[AlexTate]

This PR introduces functionality which allows users to specify classes that they want included or excluded in class DGE scatter plots. Inclusive/exclusive filtering is mutually exclusive (only one style can be chosen). Filtering takes place before subsetting features by P value, so it applies to non-differentially expressed features as well.

Additionally, the treatment condition is now listed first in the "ConditionA vs ConditionB" title of scatter_by_dge and scatter_by_dge_class plots

Remaining tasks:

• [x] Update documentation
• [x] Clean up docstrings and remove unused draft code from plotter.py
• [x] Update remaining copies of Run Config files

Closes #262

[AlexTate]

Update 12/17:

• Class filters are now case-insensitive
• tiny-config was retrieving the filter group from Run Config without proper safeguards. This has been fixed so that pre-v1.2.1 Run Configs can still be used

[taimontgomery]

Tested run and recount with Lib303 dataset with various classes excluded or included.