Smart-Fill and Mesh-Tilting (both 3-point and grid) working!

Also...   The memory corruption issue may be fixed.   The GCC compiler
was inlining static functions and this caused the G29() stack frame to
become much larger than the AVR could handle.

Marlin/ubl.cpp

@@ -27,6 +27,7 @@
 
   #include "ubl.h"
   #include "hex_print_routines.h"
+  #include "temperature.h"
 
   /**
    * These support functions allow the use of large bit arrays of flags that take very
@@ -38,6 +39,8 @@
   void bit_set(uint16_t bits[16], uint8_t x, uint8_t y) { SBI(bits[y], x); }
   bool is_bit_set(uint16_t bits[16], uint8_t x, uint8_t y) { return TEST(bits[y], x); }
 
+  int ubl_cnt=0;
+
   static void serial_echo_xy(const uint16_t x, const uint16_t y) {
     SERIAL_CHAR('(');
     SERIAL_ECHO(x);
@@ -50,9 +53,6 @@
   static void serial_echo_12x_spaces() {
     for (uint8_t i = GRID_MAX_POINTS_X - 1; --i;) {
       SERIAL_ECHOPGM("            ");
-      #if TX_BUFFER_SIZE > 0
-        MYSERIAL.flushTX();
-      #endif
       safe_delay(10);
     }
   }
@@ -70,11 +70,13 @@
   bool unified_bed_leveling::g26_debug_flag = false,
        unified_bed_leveling::has_control_of_lcd_panel = false;
 
-  int8_t unified_bed_leveling::eeprom_start = -1;
+  int16_t unified_bed_leveling::eeprom_start = -1;  // Please stop changing this to 8 bits in size
+                                                    // It needs to hold values bigger than this.
 
   volatile int unified_bed_leveling::encoder_diff;
 
   unified_bed_leveling::unified_bed_leveling() {
+    ubl_cnt++;  // Debug counter to insure we only have one UBL object present in memory.
     reset();
   }