v0.3.1

Major changes

• Add .yardopts for document generation configuration. (#26)
• Namespace errors in Arx::Error module and remove Error prefix from error classes. (#26)
• Move identifier format regular expression constant definitions from Arx::Validate to top-level namespace Arx. (#26)

Minor changes

• Rename lib/arx/exceptions.rb to lib/arx/errors.rb. (#26)
• Make Arx::Cleaner, Arx::Validate, Arx::Inspector, Arx::Link private (hidden from yard documentation). (#26)