0.9.0

• Added the -U,--update option which will eventually replace
  -L,--latest.
• Added the -D,--debug option for outputting [DEBUG] messages and
  showing which commands are actually ran during installation.
• Added support for the RUBY_INSTALL_SRC_DIR environment variable for
  controlling the default src directory.
• Added support for the RUBY_INSTALL_RUBIES_DIR environment variable for
  controlling the default installation directory.
• Added support for the RUBY_INSTALL_PKG_MANAGER environment variable for
  controlling which package manager to use by default.
• Automatically update the ruby versions and checksums if the given ruby version
  is not known.
• Added support for Void Linux's xbps package manager.

functions.sh

• Added the ruby_build_dir variable.
• Added the load_dependencies and load_dependencies_from functions.
• Added the is_unknown_ruby_version function.

rbx

• Dropped support for installing Rubinius, since it does not appear to be
  actively maintained and is not widely used anymore.