Split up pins to make it more manageable

Hopefully this is helpful to organization and future expansion….

Marlin/pins_GEN3_PLUS.h

@@ -0,0 +1,45 @@
+/**
+ * Gen3+ pin assignments
+ */
+
+#if !defined(__AVR_ATmega644P__) && !defined(__AVR_ATmega1284P__)
+  #error Oops!  Make sure you have 'Sanguino' selected from the 'Tools -> Boards' menu.
+#endif
+
+#define X_STEP_PIN         15
+#define X_DIR_PIN          18
+#define X_STOP_PIN         20
+
+#define Y_STEP_PIN         23
+#define Y_DIR_PIN          22
+#define Y_STOP_PIN         25
+
+#define Z_STEP_PIN         27
+#define Z_DIR_PIN          28
+#define Z_STOP_PIN         30
+
+#define E0_STEP_PIN        17
+#define E0_DIR_PIN         21
+
+#define LED_PIN            -1
+
+#define FAN_PIN            -1
+
+#define PS_ON_PIN         14
+#define KILL_PIN           -1
+
+#define HEATER_0_PIN       12 // (extruder)
+
+#define HEATER_BED_PIN     16 // (bed)
+#define X_ENABLE_PIN       19
+#define Y_ENABLE_PIN       24
+#define Z_ENABLE_PIN       29
+#define E0_ENABLE_PIN      13
+
+#define TEMP_0_PIN          0   // MUST USE ANALOG INPUT NUMBERING NOT DIGITAL OUTPUT NUMBERING!!!!!!!!! (pin 33 extruder)
+#define TEMP_1_PIN         -1   
+#define TEMP_2_PIN         -1
+#define TEMP_BED_PIN        5   // MUST USE ANALOG INPUT NUMBERING NOT DIGITAL OUTPUT NUMBERING!!!!!!!!! (pin 34 bed)  
+#define SDPOWER            -1
+#define SDSS               4
+#define HEATER_2_PIN       -1