use total reads for cached data, and only scale to MMR when needed
use .mmr extension for cached million mapped reads files
more flexible kwargs for ChIPSeqMiniBrowser

ip and and control can be any genomic_signal object; if BAM will be
scaled; peaks and db can be string filenames; allow peaks style
improve plot aesthetics
clean up ChIPSeqMiniBrowser.panels method
docs
improve arrayify.to_npz
bigwig support for different UCSC binning functions
clean up large arrays
improve ResultsTable.transform()
improve dataframe indexing for LazyDict
add persistence module
Merge branch 'v0.5dev' of https://github.com/daler/metaseq into v0.5dev
Merge branch 'v0.5dev' of github.com:daler/metaseq into docs

Conflicts:
	metaseq/_genomic_signal.py