BIP141: Add 520 bytes witness stack limit #303

  94 |  * It is interpreted as a pay-to-witness-script-hash (P2WSH) program.
  95 |  * The witness must consist of an input stack to feed to the script, followed by a serialized script ("witnessScript").
  96 | -* The witnessScript is popped off the initial witness stack. SHA256 of the witnessScript must match the 32-byte witness program.
  97 | -* The witnessScript is deserialized, and executed after normal script evaluation with the remaining witness stack.
  98 | +* The witnessScript (≤ 10,000 bytes) is popped off the initial witness stack. SHA256 of the witnessScript must match the 32-byte witness program.
  99 | +* The witnessScript is deserialized, and executed after normal script evaluation with the remaining witness stack (≤ 520 bytes for each stack item).

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 100 |  * The script must not fail, and result in exactly a single TRUE on the stack.
 101 |  
 102 |  If the version byte is 0, but the witness program is neither 20 nor 32 bytes, the script must fail.
 103 |  
 104 | -If the version byte is 1 to 16, no further interpretation of the witness program or witness happens.
 105 | +If the version byte is 1 to 16, no further interpretation of the witness program or witness happens, and there is no size restriction for the witness. These versions are reserved for future extensions.

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