v5.0.0: Remove dead trial endpoint

Enhancements

• Add support for --color={auto,always,never} options. And aspeak will also respect the NO_COLOR environment variable.
  • There is an edge case that aspeak will use colored output even if --color=never is specified.
    This is because aspeak uses clap to parse command line options. --color=never works only if the command line parsing is successful.
    So if you specify an invalid option, aspeak will print the error message and exit. In this case, aspeak will use colored output.
• More documentation for the rust crate.
• Minor performance improvements.
• Now you can specify the custom voice list API url in your profile(field voice_list_api in section auth).

Breaking changes

• The default trial endpoint has been removed because it was shutdown by Microsoft. Now you must set up authentication to use aspeak.
• The default voice list API url has been removed for the same reason.
• The rust API has been changed.
  • Synthesizer is now Send. Its various synthesize_* methods now takes &mut self instead of &self.
  • Now you need to use the builder pattern to create various options like TextOptions.
  • Fields of the Voice struct are now private. You can use the methods to access them.

Other changes

• The PKGBUILDs for Arch Linux is no longer stored in this repository. You can find them in the AUR.