Add a more readable syntax for enum and field indices

Testing : precheckin --full --strict-errors
Reviewer: Fare (please)

JTB impact: No
Ops impact: No

Change to config                        : No
Change to XML schema                    : No
Change to DB schema                     : No
Change to transport (timeouts, headers) : No
Any change (or new use) of OAQs         : No
Change to inter-component transactions  : No
Depends on any other checkin / bug      : No

Tests that will verify:

I extended the CL-Protobufs tests

Description:

Add a more readable syntax for enum and field indices.

For define-enum, it was (name value).
  Allow (name :index value).

For define-message, it was ((name index) ...).
  Allow (name :index index ...).
  Complain if both forms appear in the same field.



git-svn-id: http://svn.internal.itasoftware.com/svn/ita/trunk/qres/lisp/libs/cl-protobufs@561136 f8382938-511b-0410-9cdd-bb47b084005c