Implement upper/lower/initcap/firstcap functions in the expression parser (#4255)

Author: szekerest

maplexer.c

@@ -182,6 +182,10 @@ char path[MS_MAXPATHLEN];
 <EXPRESSION_STRING>tostring                    { MS_LEXER_RETURN_TOKEN(MS_TOKEN_FUNCTION_TOSTRING); }
 <EXPRESSION_STRING>commify                     { MS_LEXER_RETURN_TOKEN(MS_TOKEN_FUNCTION_COMMIFY); }
 <EXPRESSION_STRING>round                       { MS_LEXER_RETURN_TOKEN(MS_TOKEN_FUNCTION_ROUND); }
+<EXPRESSION_STRING>upper                       { MS_LEXER_RETURN_TOKEN(MS_TOKEN_FUNCTION_UPPER); }
+<EXPRESSION_STRING>lower                       { MS_LEXER_RETURN_TOKEN(MS_TOKEN_FUNCTION_LOWER); }
+<EXPRESSION_STRING>initcap                     { MS_LEXER_RETURN_TOKEN(MS_TOKEN_FUNCTION_INITCAP); }
+<EXPRESSION_STRING>firstcap                     { MS_LEXER_RETURN_TOKEN(MS_TOKEN_FUNCTION_FIRSTCAP); }
 
 <EXPRESSION_STRING>buffer                      { MS_LEXER_RETURN_TOKEN(MS_TOKEN_FUNCTION_BUFFER); }
 <EXPRESSION_STRING>difference                  { MS_LEXER_RETURN_TOKEN(MS_TOKEN_FUNCTION_DIFFERENCE); }