Rgb matrix fixes, I2C library can now retry if it has failed (qmk#2943)

* 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

* General fixes for RGB_matrix

- Complited speed support for all effects
- Fixed raindrop effects to initialized after toggle
- Fixed raindrop effects to use all available LEDs
- Fixed effect step reverse function
- Moved RGB_MATRIX_SOLID_REACTIVE under correct flag

* Documentation update for RGBmatrix

* More doc updates

* I2C library can now retry if it has failed

- Replaced the original TWIlib by LFKeyboard's modified version
- Allows for an extra argument on TWITransmitData, if blocking is set to 1 function will retry to transmit on failure. Good for noisy boards.

* RGB Matrix, use alternative I2C library

TWIlib seems to be hanging for me sometimes probably due to ISR routine. I have used i2c_master as a good alternative.

Note: this commit is for Wilba6582 to verify before merge

* Update rgb_matrix.c

* RGB matrix cleanup

- Remove TWIlib

common_features.mk

@@ -117,7 +117,7 @@ endif
 ifeq ($(strip $(RGB_MATRIX_ENABLE)), yes)
     OPT_DEFS += -DRGB_MATRIX_ENABLE
     SRC += is31fl3731.c
-    SRC += TWIlib.c
+    SRC += i2c_master.c
     SRC += $(QUANTUM_DIR)/color.c
     SRC += $(QUANTUM_DIR)/rgb_matrix.c
     CIE1931_CURVE = yes