Keyboard: Lily58 update serial.c and add OLED (#4715)

* update serial.c and add OLED

* update readme

* keymap fix

* keymap fix2

keyboards/lily58/rules.mk

@@ -1,7 +1,10 @@
-SRC += matrix.c \
-	   i2c.c \
-	   split_util.c \
-	   serial.c 
+SRC += i2c.c
+SRC += serial.c
+SRC += ssd1306.c
+
+# if firmware size over limit, try this option
+# CFLAGS += -flto
+
 # MCU name
 #MCU = at90usb1287
 MCU = atmega32u4
@@ -38,16 +41,15 @@ ARCH = AVR8
 #     CPU clock adjust registers or the clock division fuses), this will be equal to F_CPU.
 F_USB = $(F_CPU)
 
-# Interrupt driven control endpoint task(+60)
-OPT_DEFS += -DINTERRUPT_CONTROL_ENDPOINT
-
-
 # Bootloader
 #     This definition is optional, and if your keyboard supports multiple bootloaders of
 #     different sizes, comment this out, and the correct address will be loaded
 #     automatically (+60). See bootloader.mk for all options.
 BOOTLOADER = caterina
 
+# Interrupt driven control endpoint task(+60)
+OPT_DEFS += -DINTERRUPT_CONTROL_ENDPOINT
+
 # Build Options
 #   change to "no" to disable the options, or define them in the Makefile in
 #   the appropriate keymap folder that will get included automatically
@@ -65,7 +67,7 @@ UNICODE_ENABLE = no         # Unicode
 BLUETOOTH_ENABLE = no       # Enable Bluetooth with the Adafruit EZ-Key HID
 RGBLIGHT_ENABLE = no       # Enable WS2812 RGB underlight. 
 SUBPROJECT_rev1 = no
-USE_I2C = no
+USE_I2C = yes
 # Do not enable SLEEP_LED_ENABLE. it uses the same timer as BACKLIGHT_ENABLE
 SLEEP_LED_ENABLE = no    # Breathing sleep LED during USB suspend