See updated ethereumj-studio/README.md for details. Note that this
commit removes the `build-post-package.xml` ant file (for now) to
simplify the Gradle arrangement. This functionality can be re-introduced
later and more simply using Gradle's native DSL. In the meantime, both
the -core and -studio projects can be run using `gradle run` or run as
executable jars by running `gradle shadowJar` followed by the usual
`java -jar` execution of the resulting `-all` jar file found in each
project's respective `build/libs` directory.
Apply Gradle's 'maven' plugin in order to support `./gradlew install`
task, similar to `mvn install` for building and copying artifacts to the
users local ~/.m2 repository.
Previously, sources generated from the serpent antlr grammar in
ethereumj-core/src/main/antlr4 were output into the build/generated-src
directory by default. This worked from the command line without issue,
but caused issues within IDEA, because the entirety of the 'build'
directory is excluded from compilation by default when working with a
Gradle-based project in IDEA.
This change simplifies the arrangement by writing these antlr-generated
sources to the src/gen/java. A .gitignore file has been added to ensure
that transient source files don't accidentally get checked in. A readme
file has been added to explain the situation to the uninitiated.