new configurable language option: spellingStress

src/libespeak-ng/langopts.c

 			translator->langopts.lowercase_sentence = true;
 			break;
 			}
+		case V_SPELLINGSTRESS: {
+			translator->langopts.spelling_stress = true;
+			break;
+		}
 		case V_STRESSADD: { // stressAdd
                         int stress_add_set = 0;
                         int stress_add[8];

src/libespeak-ng/voice.h

 	V_WORDGAP,
 	V_INTONATION,
 	V_TUNES,
+	V_SPELLINGSTRESS,
 	V_STRESSLENGTH,
 	V_STRESSAMP,
 	V_STRESSADD,
 	{ "l_sonorant_min",   0x100+LOPT_SONORANT_MIN },
 	{ "lowercaseSentence",	V_LOWERCASE_SENTENCE },
 	{ "numbers",      V_NUMBERS },
+    { "spellingStress",    V_SPELLINGSTRESS },
     { "stressAdd",    V_STRESSADD },
     { "stressAmp",    V_STRESSAMP },
     { "stressLength", V_STRESSLENGTH },