alias: fixes exception when displaying translated help text __doc__ of aliased command shouldn't cointain non-ASCII characters, because it'll be gettext-ed later by commands.help_(). Here gettext can raise UnicodeDecodeError. Once concatenated two translatable strings into one, it become untranslatable. So this patch moves 'alias for:' from dispatch.cmdalias to commands.help_, where help texts are translated. 'alias for:' was introduced by 6e8a16dd3e30.