FR for `USAGE VARRAW` alias to `VARYING`

[GitMensch]

I did not found anything on this in the ProCOB or PG-ecpg docs, so this may be specific to citpgsql (but it seems that esql-oc also supports that in general).

From citpgsql docs they have the following varying group usages:

• VARCHAR and LONG VARCHAR - -LEN defined as PIC S9(4) COMP-5, used for "text, or binary fields, possible storage conversion, and trim" [I personally would tend to have LONG always have a 4byte length, but citpgsql does not agree with me here]
• VARYING - -LEN defined as PIC S9(4) COMP-5, used for "text, or binary fields, possible storage conversion, and trim"
• VARRAW and LONG VARRAW - -LEN defined as PIC S9(4) COMP-5, used for "binary fields, no storage conversion"

While this is, in general, related to #54; I suggest to - for now - alias VARRAW to VARYING as this would allow to preprocess sources written for citpgsql and (at least by default) we also have a generation of a 4-byte length field.

[GitMensch]

Note: the result of using VARRAW in PostgreSQL with citpgsql seems to be actually a byte parameter instead of a text one, the pgsql log shows - only for fields that are VARRAW:

DETAIL: parameters: $1 = '\x42204b20', $2 = '319331842'

(with $1 being much longer in the real log).

Allowing a USAGE that internally either uses a "binary parameter binding" (instead of a text one) or manually encodes / decodes (much worse because of additional time needed on both ends) would also work around #125.