Give numbers an explicit size

[kbuffardi]

Users are reporting different limits of the program's memory usage as well as the maximum values that are supported.

Currently, we are using int which typically are at least 32 bit, but depend on the C++ implementation.

Update the program so it uses the int32_t data type to force all builds to have the consistent limit.

The acceptable numbers should be displayed to the user after the welcome message, using the line of output:

(Limited to whole numbers between -2,147,483,648 and 2,147,483,647)