CA PV: Write any 32 bit long, signed or unsigned

[kasemir]

Channel Access doesn't have "long" (64 bit).
It only has 32 bit "int", and they're signed.

A value of 0x80000000, while a 32 bit value, exceeds the value range of a 32 bit signed integer. It was then written as a double, losing precision.
Now the JCA_PV detects if such a long value fits into 32 bits as a signed integer.

In the display builder or probe, when selecting Hex as the display format this now allows entering and displaying any values from 0x00000000 to 0xFFFFFFFF, whereas previously numbers beyond 0x7FFFFFFF could not be entered, had to enter negative values.