Feature/date time mstimer clock (#861)

* Added daylight savings time calculation module with unit testing.

* Added datetime daylight savings time and clock API

* Added basic datetime_local() clock using mstimer as basis and time-sync option.  Integrated clock with ports/stm32f4xx example.

src/bacnet/datetime.h

@@ -318,18 +318,45 @@ bool datetime_local(
     BACNET_TIME *btime,
     int16_t *utc_offset_minutes,
     bool *dst_active);
+/* UTC Offset API */
 BACNET_STACK_EXPORT
 int16_t datetime_utc_offset_minutes(void);
 BACNET_STACK_EXPORT
 bool datetime_utc_offset_minutes_set(int16_t minutes);
+/* Daylight Savings Time API */
 BACNET_STACK_EXPORT
-bool datetime_dst_active(void);
+bool datetime_dst_enabled(void);
 BACNET_STACK_EXPORT
-bool datetime_dst_range(BACNET_DATE_RANGE *dst_range);
+void datetime_dst_enabled_set(bool flag);
 BACNET_STACK_EXPORT
-bool datetime_dst_range_set(BACNET_DATE_RANGE *dst_range);
+bool datetime_dst_ordinal_range(
+    uint8_t *start_month,
+    uint8_t *start_week,
+    uint8_t *start_day,
+    uint8_t *end_month,
+    uint8_t *end_week,
+    uint8_t *end_day);
+BACNET_STACK_EXPORT
+bool datetime_dst_ordinal_range_set(
+    uint8_t start_month,
+    uint8_t start_week,
+    BACNET_WEEKDAY start_day,
+    uint8_t end_month,
+    uint8_t end_week,
+    BACNET_WEEKDAY end_day);
+BACNET_STACK_EXPORT
+bool datetime_dst_date_range(
+    uint8_t *start_month,
+    uint8_t *start_day,
+    uint8_t *end_month,
+    uint8_t *end_day);
+BACNET_STACK_EXPORT
+bool datetime_dst_date_range_set(
+    uint8_t start_month, uint8_t start_day, uint8_t end_month, uint8_t end_day);
+/* BACnet TimeSynchronization service handler API */
 BACNET_STACK_EXPORT
 void datetime_timesync(BACNET_DATE *bdate, BACNET_TIME *btime, bool utc);
+/* Initialization for integration with a clock */
 BACNET_STACK_EXPORT
 void datetime_init(void);