Used in activation and determining the counts to concentrated flow
conversion.

Sets shift to zero - Scan will be marked invalid when checking for consistent temperature.

Everything works but en/disabling of file menu items.
Temporary File menu fix - to be resolved in new workflow

For scans with no valid points, point from the most recently displayed
graph with points would appear on the graph.

Test code is only active when running in python env.
When code is frozen (i.e. bundled with PyInstaller), the test code is
not active

If either is zero, skip calculating shift
If SMPS is zero, do not pass compare_smps check

Code to be refactored with new workflow

Also added sigmoid fit on a single scan

Related #40

Related #7

Related #44

Related #13

Legend tweaks, legends moved, typos fixed.
Temperature lines rearranged

Set np.exp min and max to be relative to float limits

Related #65

Also includes clean up of old code
Updating of vulture config
Adding to README how to use vulture