Improving FIX mode

[c3d]

Solving this by adding a new setting, MinimumSignificantDigits.

This selects the minimum number of significant digits before switching to scientific notation in FIX mode.

The default value is 0, which is similar to how HP calculators perform. For example, with 2 FIX, the value 0.055 will display as 0.06, and 0.0055 will display as 0.01.

A higher value will switch to scienfic mode to show at least the given number of digits. For instance, with 2 FIX, if the value is 1, then 0.055 will still display as 0.06 but 0.0055 will display as 5.50E-3. If the value is 2, then 0.055 will display as 5.5E-2.

In other words, setting the value to 0 emulates the behaviour of HP calculators. Setting the value to 34 will switch to scientific notation if not all digits can be displayed