elrond-wasm 0.27.0

• Fixed certain compilation error messages. The previous implementation of the macro preprocessor would have concealed the location of many issues.
• Changed implementation of require!:
  • require! no longer returns a SCResult type, when the condition is false it now stops the transaction immediately, via signal_error;
  • require! now accepts message formatting;
  • require_old! gives access to the old implementation.
• The Rust testing framework can now handle panics and async calls.
• ABI bugfix - an issue regarding nested types.
• meta crate build also attempts to call wasm-opt after building the contracts.
• Refactored CodeMetadata and added "payable by SC" field.
• Empty contract template.