Add dash if alias does not have dash

[tbpgr]

Sample Code

alias o => option -o

require 'thor'
class SampleCLI < Thor
  desc "command usage", "command desc"
  option "opt", aliases: "o", type: :boolean
  def command(name)
    puts "opt on" if options['opt']
    puts "command #{name}"
  end
end

SampleCLI.start(ARGV)

Actual

Alias help does not have a dash.

$ ruby sample.rb command hoge
command hoge
$ ruby sample.rb command -o hoge
opt on
command hoge
$ ruby sample.rb command --opt hoge
opt on
command hoge
ruby sample.rb help command
Usage:
  sample.rb command usage

Options:
  o, [--opt], [--no-opt]

command desc

Expected

Alias help has a dash.

$ ruby sample.rb command hoge
command hoge
$ ruby sample.rb command -o hoge
opt on
command hoge
$ ruby sample.rb command --opt hoge
opt on
command hoge
ruby sample.rb help command
Usage:
  sample.rb command usage

Options:
  -o, [--opt], [--no-opt]

command desc

Related Issue

#159