batch changes to saxs merge

- change lambdamin from 0.005 to 0.025
- add two other fallbacks for non-SPD Sigma matrix in rescaling step
- correct bug in remove_redundant
- change filename display to use os.path.basename
- display M in cleanup step
descrease s by 0.001 if s==d
drop MAD criterion, replace by error > 20*median
make jitter relative to tau
Major change to fitting procedure

Fit all parameters explicitly and at once, using scipy.optimize.minimize