Use better text descriptions. Holding down rate buttons now increase/decrease

src/localisation/currency.h

@@ -49,6 +49,7 @@ typedef enum {
 } CURRENCY_AFFIX;
 
 #define CURRENCY_SYMBOL_MAX_SIZE 8
+#define CURRENCY_RATE_MAX_NUM_DIGITS 9
 
 // Currency format specification - inspired by OpenTTD
 typedef struct currency_descriptor {

src/localisation/string_ids.h

@@ -2672,6 +2672,8 @@ enum {
 	STR_LOADSAVE_DEFAULT = 5891,
 	STR_LOADSAVE_DEFAULT_TIP = 5892,
 
+	STR_RATE_INPUT_TITLE = 5893,
+	STR_RATE_INPUT_DESC = 5894,
 	// Have to include resource strings (from scenarios and objects) for the time being now that language is partially working
 	STR_COUNT = 32768
 };