feat(syntax): support for trailing comma (#179)

in struct declarations and definitions, and also
in function declarations and function calls,
including extension functions and some builtins

CHANGELOG.md

@@ -17,6 +17,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 - Update the `dump` function to handle addresses: PR [#175](https://github.com/tact-lang/tact/pull/175)
+- Support trailing commas for struct fields and function arguments: PR [#179](https://github.com/tact-lang/tact/pull/179)
 - The implicit empty `init` function is now present by default in the contract if not declared: PR [#167](https://github.com/tact-lang/tact/pull/167)
 - `@stdlib/stoppable` now imports `@stdlib/ownable` so the programmer does not have to do it separately: PR [#193](https://github.com/tact-lang/tact/pull/193)
 - Support escape sequences for strings (`\\`, `\"`, `\n`, `\r`, `\t`, `\v`, `\b`, `\f`, `\u{0}` through `\u{FFFFFF}`, `\u0000` through `\uFFFF`, `\x00` through `\xFF`): PR [#192](https://github.com/tact-lang/tact/pull/192)