Adding annotation to the convolution windows

[redst4r]

Hi,

I often need to look up what window i in CNV space (adata.obsm['X_cnv'][:,i]) corresponds to in gene space (i.e. which chromosome, which genes, which coordinates). Might relate to #50

Hence I added this information in adata.uns['cnv']['var']. Its pretty much the equivalent of .var in the epxression AnnData, just for the CNV-space.

For example, to get all windows from chromosome one, you'd do

ix_chr1= adata.uns['cnv']['var'].chromosome=="chr1"
adata.obsm['X_cnv'][:, ix_chr1]

[grst]

Something went wrong with the black reformat (didn't read the line length from the config 🤔). Just fixing these to make the diff smaller & the review easier.

[grst]

Superseded by #132