show no positions as 0 gross leverage on gross leverage plot

add 2022 inflation interesting period

extract resulting_amount from transaction dict

round performance stats to a reasonable number of decimal places

MAINT: updates for pandas 2 and mpl 3.7

DOC: add usage guide links to docstrings

TST: fix a test giving different results on amd64 vs arm64

TST: remove example notebook tests

BLD: simplify setup.py (dependencies will come from elsewhere)

remove sklearn dependency