v0.2.0

• Updated wasmi to v0.31.2
• Refactoring code base
• Added crypto functions
  • env0::fast_hash
  • env0::secure_hash
  • env0::sig_verfiry
• Added possibility to call a contract with raw parameters
  • env0::call_contract_params
• Added a function to get the ContractId of the caller of the given contract
  • env0::caller
• Implemented function to retrieve transaction fields (In place of get_tx_sender)
  • env1::tx
• New versions of the function
  • env1::get_balance
  • env1::transfer
  • env1::issue
  • env1::get_payments
  • env1::get_payment_asset_id
  • env1::get_payment_amount
• Various minor fixes and tweaks