SignedIntegerToInteger issue.

[ryanayearsley]

When attempting to convert signed integers, negatives don't convert correctly.

I'm using the signingType = CopyBookFieldSigningType.LAST_BYTE_EBCDIC_BIT5 (all others throw an exception)

and the annotation
@CopyBookLine("05 IMINVCHG-QTY PIC S9(07).")

Example 1: Positive
input: 000000B
output (expected): 2
output: 2

Example 2: Negative
input: 000000K
output (expected): -2
output: 11