Cu75 iso fix (#2801)

* Added Modular keyboards L,R and NUM

Created code modules for the 3 modules of the modular keyboard.
Original idea by MechboardsUK. Uses i2c implementation similar to lets
split

* Remove modular from master

This is to fix incorrect branching

* CU75 keymap fix

Incorrect keymap now fixed

keyboards/cu75/cu75.h

@@ -110,8 +110,8 @@ void click(uint16_t freq, uint16_t duration);
 #define LAYOUT_iso( \
     k01, k02, k03, k04, k05, k06, k07, k08, k09, k0A, k0B, k0C, k0D, k0E, k0F, k0G, \
     k11, k12, k13, k14, k15, k16, k17, k18, k19, k1A, k1B, k1C, k1D,      k1E, k1G, \
-    k21,   k22, k23, k24, k25, k26, k27, k28, k29, k2A, k2B, k2C, k2D,    k3D, k2F, \
+    k21,   k22, k23, k24, k25, k26, k27, k28, k29, k2A, k2B, k2C, k2D,    k2E, k2F, \
-    k31,    k32, k33, k34, k35, k36, k37, k38, k39, k3A, k3B, k3C,        k2E, k3F, \
+    k31,    k32, k33, k34, k35, k36, k37, k38, k39, k3A, k3B, k3C,        k3D, k3F, \
     k41, k42, k43, k44,  k45, k46, k47, k48, k49, k4A, k4B, k4C,      k4D, k4E, k4F, \
     k51, k52, k53,        k54,      k57,       k59,        k5A, k5B, k5C, k5D, k5E, k5F \
 ) { \