Make G26 work with all mesh leveling.

Example Configuration.h files are not updated yet.   You need to cross
your settings over to the default Configuration.h file in the \Marlin
directory.   (UBL_G26_MESH_VALIDATION enablement has moved to a new
location in the file.)

Marlin/bitmap_flags.h

@@ -0,0 +1,38 @@
+/**
+ * Marlin 3D Printer Firmware
+ * Copyright (C) 2016, 2017 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
+ *
+ * Based on Sprinter and grbl.
+ * Copyright (C) 2011 Camiel Gubbels / Erik van der Zalm
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef _BITMAP_FLAGS_H_
+#define _BITMAP_FLAGS_H_
+
+#include "macros.h"
+
+/**
+ * These support functions allow the use of large bit arrays of flags that take very
+ * little RAM. Currently they are limited to being 16x16 in size. Changing the declaration
+ * to unsigned long will allow us to go to 32x32 if higher resolution meshes are needed
+ * in the future.
+ */
+FORCE_INLINE void bit_clear(uint16_t bits[16], const uint8_t x, const uint8_t y) { CBI(bits[y], x); }
+FORCE_INLINE void bit_set(uint16_t bits[16], const uint8_t x, const uint8_t y) { SBI(bits[y], x); }
+FORCE_INLINE bool is_bit_set(uint16_t bits[16], const uint8_t x, const uint8_t y) { return TEST(bits[y], x); }
+
+#endif // _BITMAP_FLAGS_H_