#2 COMP-6 support

[Pawel Maczka]

I think that it can be done based on COMP-3: just parse COMP-6 founded in copybooks similar to COMP-3 so that items based on this has all requires attributes like "usage", "decimal", "display-length" properly set.

Example:
03 SUJ001 PIC 9(6) COMP-6.

now creates:
<item display-length="9" level="03" name="SUJ001" numeric="true" picture="9(6)COMP-6" position="1" redefined="true" storage-length="9"/>

should be:
<item display-length="6" level="03" name="SUJ001" numeric="true" picture="9(6)COMP-6" position="1" scale="0" signed="false" storage-length="3" usage="computational-6"/>