v1.9.0

Version used for the "v9" runs of l2gen. Differences from v8 are:

• Changed the logic of the masking step such that when smaller boxes and stripes (e.g. size=32) mask a set of channels, those channels are also masked from the correlation matrix when performing the larger boxes and stripes, such that a small high-correlation region will not end up masking an entire sideband.
• Fine-tuned the box/stripe chi2 cuts in l2gen by staring at some histograms.