Add a "path" argument to Sequel::Generators::Base.source_root

[akxcv]

Sequel::Generators::Base.source_root method does not take a path argument, which diverges from Rails::Generators::Base API. The path argument is very useful for creating custom generators with templates, for example:

# lib/generators/foo/install/install_generator.rb
class Foo::Generators::InstallGenerator < ::Sequel::Generators::Base
  include Sequel::Generators::Migration
  source_root File.expand_path('../templates', __FILE__) # will not work, but would work with Rails
  # ...
end

# templates are stored in lib/generators/foo/install/templates

This behaviour can be observed since Rails 3.0.