Develop helpfile

further refinements to helpfile.

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UTILITY cagegory of sx help now reads

UTILITY
   EC MATH
        ec-add-modp                Calculate the result of INTEGER + INTEGER.
        ec-multiply                Multiply an integer and a point together.
        ec-tweak-add               Calculate the result of POINT + INTEGER * G.
   FORMAT (BASE 58)
        base58-decode              Convert from base58 to hex
        base58-encode              Convert from hex to base58
   FORMAT (BASE58CHECK)
        base58check-decode         Convert from base58check to hex
        base58check-encode         Convert from hex to base58check
        decode-addr                Decode a address from base58check form to internal RIPEMD representation
        encode-addr                Encode an address from internal RIPEMD representation to base58check form
   FORMAT (WIF)
        secret-to-wif              Convert a secret exponent value to Wallet Import Format
        wif-to-secret              Convert a Wallet Import Format to secret exponent value.
   HASHES
        ripemd-hash                RIPEMD hash data from STDIN.
        sha256                     Perform SHA256 hash of data.
   MISC
        qrcode                     Generate Bitcoin QR codes offline.
   SATOSHI MATH
        btc                        Convert Satoshis into Bitcoins.
        satoshi                    Convert Bitcoins into Satoshis.

See 'sx help COMMAND' for more information on a specific command.
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