Minor cleanup of operand type and traits code in isa_parser.py.

Minor cleanup of operand type and traits code in isa_parser.py.

arch/isa_parser.py:
    Minor cleanup of operand type and traits code:
    - build operand size map right away when types are defined
    instead of waiting to do it lazily
    - check that operand types have been defined before operands
    - don't use 'type' as a variable name
    - use isinstance() instead of checking for types directly

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extra : convert_revision : 099c1ee8d490f9c38316749bf87209388c55c971