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_adv.h

@@ -634,7 +634,7 @@
 
 //#define HOMING_BACKOFF_POST_MM { 2, 2, 2 }  // (mm) Backoff from endstops after homing
 
-//#define QUICK_HOME                          // If G28 contains XY do a diagonal move first
+#define QUICK_HOME                          // If G28 contains XY do a diagonal move first
 //#define HOME_Y_BEFORE_X                     // If G28 contains XY home Y before X
 //#define CODEPENDENT_XY_HOMING               // If X/Y can't home without homing Y/X first
 
@@ -1056,7 +1056,7 @@
   #endif
 
   // BACK menu items keep the highlight at the top
-  //#define TURBO_BACK_MENU_ITEM
+  #define TURBO_BACK_MENU_ITEM
 
   /**
    * LED Control Menu
@@ -1096,7 +1096,7 @@
 //#define LCD_TIMEOUT_TO_STATUS 15000
 
 // Add an 'M73' G-code to set the current percentage
-//#define LCD_SET_PROGRESS_MANUALLY
+#define LCD_SET_PROGRESS_MANUALLY
 
 // Show the E position (filament used) during printing
 //#define LCD_SHOW_E_TOTAL
@@ -1109,7 +1109,7 @@
   //#define PRINT_PROGRESS_SHOW_DECIMALS // Show progress with decimal digits
   #define SHOW_REMAINING_TIME          // Display estimated time to completion
   #if ENABLED(SHOW_REMAINING_TIME)
-    //#define USE_M73_REMAINING_TIME     // Use remaining time from M73 command instead of estimation
+    #define USE_M73_REMAINING_TIME     // Use remaining time from M73 command instead of estimation
     #define ROTATE_PROGRESS_DISPLAY    // Display (P)rogress, (E)lapsed, and (R)emaining time
   #endif
 #endif
@@ -1756,7 +1756,7 @@
 //
 // G2/G3 Arc Support
 //
-#define ARC_SUPPORT                 // Disable this feature to save ~3226 bytes
+//#define ARC_SUPPORT                 // Disable this feature to save ~3226 bytes
 #if ENABLED(ARC_SUPPORT)
   #define MM_PER_ARC_SEGMENT      1 // (mm) Length (or minimum length) of each arc segment
   //#define ARC_SEGMENTS_PER_R    1 // Max segment length, MM_PER = Min
@@ -3089,7 +3089,7 @@
 /**
  * Disable all Volumetric extrusion options
  */
-//#define NO_VOLUMETRICS
+#define NO_VOLUMETRICS
 
 #if DISABLED(NO_VOLUMETRICS)
   /**