update docs for 1.0.9

update doc

drop 3.9, add 3.14

document support for Python 3.9 to 3.13

improve error management; shunt .run() with string to .eval()

emergency fix for handling errors, exposed by lmfit

Procedures: move 'build signature' to _signature() method, use in repr

more work to make exception messages more Python like

update doc to describe audit by IBM security research group

update docs