BUG: negative INTIAL

[DanielePlacidoPolito]

Describe the bug
Negative values for flag INTIAL do not work as expected or not work at all in input file *operations.txt may not work as expected or not work at all

To Reproduce
Steps to reproduce the behavior:

1. Go to *operations.txt
2. Click on one of the sheets (CHAN, STR_MIX, STR_SC, STR_STAB, Z_JACKET)
3. Scroll down respectively to line 4, 23, 21, 23, 19
4. Set an allowed negative value
5. Save and run the software
6. See error

Expected behavior
The software should load input values from auxiliary input flies

Desktop (please complete the following information):

• OS: Windows 10