`RLP` constants renaming

[OlivierBBB]

The constants

RLP_PREFIX_INT_SHORT    128
RLP_PREFIX_INT_LONG     183

carry the wrong name, it should be

RLP_PREFIX_BYTE_ARRAY_SHORT    128
RLP_PREFIX_BYTE_ARRAY_LONG     183
RLP_PREFIX_LIST_SHORT          192
RLP_PREFIX_LIST_LONG           247

The constants 128 and 183 feature in the RLP-ization of byte arrays, e.g. of address ∈ B_{20}. Also the RLP-ization of integers is a special case of the RLP-ization of byte arrays, via the BE: N -> B function integers to byte arrays.