Until the antlr-parser can successfully type-check the non-mockup
version.

Avoids having to manually pass --refresh-dependencies to Gradle.

B2Program doesn't need to use ANTLR directly. antlr-parser already
contains the generated parser and has its own dependency on ANTLR.

Allows easier updating of the wrappers using:

./gradlew wrapper --gradle-version=X.Y.Z