STM32F1 HAL

Adding files for STM32F1 HAL based on libmaple/stm32duino core.
Current persistent_store uses cardreader changes to be sent in separate
commit, but could be changed to use i2c eeprom.

Marlin/src/pins/pins_5DPRINT.h

@@ -76,6 +76,14 @@
 
 #define LARGE_FLASH        true
 
+//
+// Servos
+//
+#define SERVO0_PIN        41
+#define SERVO1_PIN        42
+#define SERVO2_PIN        43
+#define SERVO3_PIN        44
+
 //
 // Limit Switches
 //
@@ -102,7 +110,9 @@
 #define E0_DIR_PIN         35   // A7
 #define E0_ENABLE_PIN      11   // C1
 
-
+//
+// Digital Microstepping
+//
 #define X_MS1_PIN          25   // B5
 #define X_MS2_PIN          26   // B6
 #define Y_MS1_PIN           9   // E1