Version 1.4

Bug fixes and CI/docs updates.

Fixes:

• chiSquareTest() and linearityTest() no longer crash with an AttributeError when the retrieval did not converge; they now return the documented NaN/False result instead.
• The deprecated disturbance keyword now raises an error pointing to perturbation instead of being silently discarded.
• getJacobian()/getJacobian_external() no longer silently misapply a user-supplied perturbation dict when its key order differs from x_vars+b_vars.
• chiSquareTest() and linearityTest() now use a numerically stable, version-independent eigendecomposition, fixing chi2/linearity results that could previously vary between numpy/scipy versions.
• plotIterations() no longer swallows unrelated errors and fixes an off-by-one in the marked best-iteration index.

Other:

• Tested with Python 3.10-3.14 (CI matrix updated).
• Documentation no longer references Python 2.7; install instructions updated to python -m pip install ..