maintainability: pass Translator as to towlower2() instead of using a global

src/libespeak-ng/compiledict.c

 			if (c2 == 0)
 				break;
 			if (iswupper(c2))
-				utf8_out(towlower2(c2), p);
+				utf8_out(towlower2(c2, translator), p);
 			else
 				all_upper_case = false;
 			p += ix;

src/libespeak-ng/numbers.c

 		if (iswupper(letter))
 			Lookup(tr, "_cap", capital);
 	}
-	letter = towlower2(letter);
+	letter = towlower2(letter, tr);
 	LookupLetter(tr, letter, word[n_bytes], ph_buf, control & 1);
 
 	if (ph_buf[0] == 0) {

src/libespeak-ng/readclause.c

 	return CLAUSE_NONE;
 }
 
-int towlower2(unsigned int c)
+int towlower2(unsigned int c, Translator *translator)
 {
 	// check for non-standard upper to lower case conversions
 	if (c == 'I' && translator->langopts.dotless_i)

src/libespeak-ng/readclause.h

 extern PARAM_STACK param_stack[];
 
  int clause_type_from_codepoint(uint32_t c);
-int towlower2(unsigned int c); // Supports Turkish I
+int towlower2(unsigned int c, Translator *translator); // Supports Turkish I
 int Eof(void);
 const char *WordToString2(unsigned int word);
 int Read4Bytes(FILE *f);

src/libespeak-ng/translate.c

 	// there is a list of character codes to be substituted with alternative codes
 
 	if (iswupper(c_lower = c)) {
-		c_lower = towlower2(c);
+		c_lower = towlower2(c, tr);
 		upper_case = 1;
 	}
 
 				new_c = replace_chars[ix+1];
 				break;
 			}
-			if ((word >> 16) == (unsigned int)towlower2(next_in)) {
+			if ((word >> 16) == (unsigned int)towlower2(next_in, tr)) {
 				new_c = replace_chars[ix+1];
 				ignore_next = true;
 				break;
 		if ((option_sayas2 == SAYAS_KEY) && (c != ' ')) {
 			if ((prev_in == ' ') && (next_in == ' '))
 				option_sayas2 = SAYAS_SINGLE_CHARS; // single character, speak its name
-			c = towlower2(c);
+			c = towlower2(c, tr);
 		}
 
 
 				}
 
 				if (iswupper(c)) {
-					c = towlower2(c);
+					c = towlower2(c, tr);
 
 					if ((j = tr->langopts.param[LOPT_CAPS_IN_WORD]) > 0) {
 						if ((j == 2) && (syllable_marked == false)) {
 							// lower case followed by upper case in a word
 							if (UpperCaseInWord(tr, &sbuf[ix], c) == 1) {
 								// convert to lower case and continue
-								c = towlower2(c);
+								c = towlower2(c, tr);
 							} else {
 								c = ' '; // lower case followed by upper case, treat as new word
 								space_inserted = true;