voices: support a status annotation in voice files

CHANGELOG.md

 *  Group languages by their language family and use BCP47 compliant names.
 *  Support for Windows and BSD platforms.
 *  Removed support for WinCE, MS-DOS and RiscOS.
-*  Add support for a `maintainer` field in voice files for tracking voice
-   maintenance.
+*  Add support for `maintainer` and `status` field in voice files for tracking
+   voice maintenance.
 
 build:
 

docs/voices.md

 files. If no maintainer is specified, the voice does not currently have an
 active maintainer.
 
+### status
+
+	status <status level>
+
+Specifies how advanced the support for the language is:
+
+* `testing` -- Provides the basic level of support, with basic pronunciation
+   rules. Requires feedback from a native speaker to help improve the voice.
+
+* `mature` -- The language is well supported. It has been improved by, or with
+  support from, a native speaker.
+
 ## Voice Attributes
 
 ### pitch

src/libespeak-ng/voices.c

 	V_DICTIONARY,
 
 	V_MAINTAINER,
+	V_STATUS,
 
 	// these affect voice quality, are independent of language
 	V_FORMANT,
 	{ "gender",       V_GENDER },
 
 	{ "maintainer",   V_MAINTAINER },
+	{ "status",       V_STATUS },
 
 	{ "formant",      V_FORMANT },
 	{ "pitch",        V_PITCH },
 			}
 			break;
 		case V_MAINTAINER:
+		case V_STATUS:
 			break;
 		default:
 			if ((key & 0xff00) == 0x100)