add options for representing floating-point numbers in debugger

I do really appreciate the option to select "Compact Float" or "Scientific Float" within the "Change Value Display Format" under the "Locals" pane of the debugger.

It would sometimes be very useful if there were a couple of more options:
1. The `std::hexfloat` representation produced by `std::sstream`.
2. Breaking the number into a normalized value and a integral power of 2, as does the `std::frexp()` function.