code cleanup: move stressLength, stressAdd and stressAmp handling in LoadVoice()

From now on, stressLength must be set before stressAdd because
stressLength will overwrite any previous value. Usually stressLength is
set in a language file and stressAdd in a voice file.

Previously the order of the two commands didn't matter.

CHANGELOG.md

 
 *  Add support for speechPlayer.
 *  Add more tests to check the various parts of espeak-ng.
-*  Various changes to clean up the codebase.
+*  Various changes to clean up the codebase (Juho Hiltunen)
 *  Restructure "option brackets" language option to "brackets" and "bracketsAnnounced".
+*  Restructure "stressLength" and "stressAdd" language option
 *  New Language option: "lowercaseSentence" for ending a sentence if a period is followed by a lower case letter.
 *  Added voice variants
 *  Renamed zh to cmn (Mandarin)

docs/voices.md

 `stressLength` values. They are used in the voice variant files in
 `espeak-ng-data/voices/!v` to give some variety. Negative values may be used.
 
+Note that setting `stressLength` after `stressAdd`  will overwrite this value.
+`stressLength` must be set before `stressAdd`.
+
 ### stressAmp
 
 	stressAmp <8 integer values>

src/libespeak-ng/voices.c

 	int tone_only = control & 2;
 	bool language_set = false;
 	bool phonemes_set = false;
-	int stress_amps_set = 0;
-	int stress_lengths_set = 0;
-	int stress_add_set = 0;
 	int conditional_rules = 0;
 
 	char voicename[40];
 	char path_voices[sizeof(path_home)+12];
 
 	int dict_min = 0;
-	int stress_amps[8];
-	int stress_lengths[8];
 	int stress_add[8];
 	char names[8][40];
 	char name1[40];
 				voice->formant_factor = (int)((1+factor/4) * 256); // nominal formant shift for a different voice pitch
 			}
 			break;
-		case V_STRESSLENGTH: // stressLength
-			stress_lengths_set = Read8Numbers(p, stress_lengths);
+		case V_STRESSLENGTH: {// stressLength
+			if (translator) {
+				int stress_lengths_set = 0;
+				int stress_lengths[8];
+				stress_lengths_set = Read8Numbers(p, stress_lengths);
+				for (ix = 0; ix < stress_lengths_set; ix++) {
+					translator->stress_lengths[ix] = stress_lengths[ix];
+				}
+			} else
+				fprintf(stderr, "Cannot set stressLength: language not set, or is invalid.\n");
+
 			break;
-		case V_STRESSAMP: // stressAmp
-			stress_amps_set = Read8Numbers(p, stress_amps);
+		}
+		case V_STRESSAMP: { // stressAmp
+			if (translator) {
+				int stress_amps_set = 0;
+				int stress_amps[8];
+				stress_amps_set = Read8Numbers(p, stress_amps);
+				for (ix = 0; ix < stress_amps_set; ix++) {
+					translator->stress_amps[ix] = stress_amps[ix];
+				}
+			} else
+				fprintf(stderr, "Cannot set stressAmp: language not set, or is invalid.\n");
 			break;
-		case V_STRESSADD: // stressAdd
-			stress_add_set = Read8Numbers(p, stress_add);
+		}
+		case V_STRESSADD: { // stressAdd
+			if (translator) {	
+				int stress_add_set = 0;
+				stress_add_set = Read8Numbers(p, stress_add);
+
+				for (ix = 0; ix < stress_add_set; ix++) {
+					translator->stress_lengths[ix] += stress_add[ix];
+				}
+			} else
+				fprintf(stderr, "Cannot set stressAdd: language not set, or is invalid.\n");
+
 			break;
+		}
 		case V_INTONATION: // intonation
 			sscanf(p, "%d", &option_tone_flags);
 			if ((option_tone_flags & 0xff) != 0) {
 
 	voice->width[0] = (voice->width[0] * 105)/100;
 
-	// relative lengths of different stress syllables
-	for (ix = 0; ix < stress_lengths_set; ix++)
-		translator->stress_lengths[ix] = stress_lengths[ix];
-	for (ix = 0; ix < stress_add_set; ix++)
-		translator->stress_lengths[ix] += stress_add[ix];
-	for (ix = 0; ix < stress_amps_set; ix++) {
-		translator->stress_amps[ix] = stress_amps[ix];
-	}
-
 	return voice;
 }