Anycubic Mega Zero updates (#199)

- Fix bootscreen
- Fix Y minimal position
- Enable support for M73 (Current percentage/Remaining time)
- Enable individual axis homing menus
- Enable quick homing for XY
- Enable "back" menu item at the top
- Enable Mesh Bed Leveling (including LCD leveling sub-menu)
- To save space:
  - Disable Arc support
  - Disable Volumetric extrusion options
  - Enable Slim LCD Menus

config/examples/AnyCubic/Mega Zero/Configuration.h

@@ -1140,8 +1140,8 @@
 #define Y_BED_SIZE 220
 
 // Travel limits (mm) after homing, corresponding to endstop positions.
-#define X_MIN_POS -10
-#define Y_MIN_POS -10
+#define X_MIN_POS -9
+#define Y_MIN_POS 0
 #define Z_MIN_POS 0
 #define X_MAX_POS X_BED_SIZE
 #define Y_MAX_POS Y_BED_SIZE
@@ -1250,13 +1250,13 @@
 //#define AUTO_BED_LEVELING_LINEAR
 //#define AUTO_BED_LEVELING_BILINEAR
 //#define AUTO_BED_LEVELING_UBL
-//#define MESH_BED_LEVELING
+#define MESH_BED_LEVELING
 
 /**
  * Normally G28 leaves leveling disabled on completion. Enable
  * this option to have G28 restore the prior leveling state.
  */
-//#define RESTORE_LEVELING_AFTER_G28
+#define RESTORE_LEVELING_AFTER_G28
 
 /**
  * Enable detailed logging of G28, G29, M48, etc.
@@ -1355,12 +1355,12 @@
  * Add a bed leveling sub-menu for ABL or MBL.
  * Include a guided procedure if manual probing is enabled.
  */
-//#define LCD_BED_LEVELING
+#define LCD_BED_LEVELING
 
 #if ENABLED(LCD_BED_LEVELING)
   #define MESH_EDIT_Z_STEP  0.025 // (mm) Step size while manually probing Z axis.
   #define LCD_PROBE_Z_RANGE 4     // (mm) Z Range centered on Z_MIN_POS for LCD Z adjustment
-  //#define MESH_EDIT_MENU        // Add a menu to edit mesh points
+  #define MESH_EDIT_MENU        // Add a menu to edit mesh points
 #endif
 
 // Add a menu item to move between bed corners for manual bed adjustment
@@ -1766,7 +1766,7 @@
  * just remove some extraneous menu items to recover space.
  */
 //#define NO_LCD_MENUS
-//#define SLIM_LCD_MENUS
+#define SLIM_LCD_MENUS
 
 //
 // ENCODER SETTINGS
@@ -1820,7 +1820,7 @@
 //
 // Add individual axis homing items (Home X, Home Y, and Home Z) to the LCD menu.
 //
-//#define INDIVIDUAL_AXIS_HOMING_MENU
+#define INDIVIDUAL_AXIS_HOMING_MENU
 
 //
 // SPEAKER/BUZZER