document data jsons with reference links, notes, and remove old unnec…

…essary data

refactor schools method to catch when too small schools are generated

refactor to handle generating very small pop sizes

reinstating checks when loading data jsons

plotting fix for household method

Merge pull request #475 from amath-idm/fix-changelog-dates

fixing dates

pip allowable

fast network implementation

default n defined, contact counter updated and statistical test modified

adding statistical testing methods 1.6.1