Questbook-TzSign

• tzSignAPI.ts is the tzSign API wrapper
• multisig.ts is the class having the useful fuctions requested here.
  • Currently createXTZTransaction exists instead of createMultiTransaction
  • Rest is all supported, from creating the multisig to adding the transactions in it, signing them and eventually sending them.
• index.ts is used for testing the multisig and demonstrating its use.