Refactor and updates to TKC1800 code (#8472)

* TKC1800: updated to support QMK-DFU bootloader

* TKC1800: updated to support QMK-DFU bootloader

* TKC1800: Updated to utilize common I2C and OLED code

* Refactor OLED code in VIA keymap

* Fix for screen disconnected error.

* Added changelog for breaking change process

docs/ChangeLog/20200530/PR8472.md

@@ -0,0 +1,42 @@
+# Refactor of TKC1800 to use common OLED code
+
+[#8472](https://github.com/qmk/qmk_firmware/pull/8472) Modifies the default firmware for TKC1800 to use the in-built I2C and OLED drivers, instead of including and depending on its own set of libraries for the following functionality:
+- SSD1306 display
+- i2c for OLED
+
+This allows current TKC1800 firmware to advance with updates to those drivers, which are shared with other keyboards.
+
+## To migrate existing TKC1800 firmware:
+
+[Changes to `config.h`](https://github.com/qmk/qmk_firmware/pull/8472/files#diff-d10b26e676b4a55cbb00d71955116526):
+- Remove `#define SSD1306OLED` from config.h
+
+[Changes to `tkc1800.c`](https://github.com/qmk/qmk_firmware/pull/8472/files#diff-3b35bd30abe89c8110717c6972cd2cc5):
+- Add the following to avoid debug errors on HID_listen if the screen is not present
+```c
+void keyboard_pre_init_kb(void) {
+  setPinInputHigh(D0);
+  setPinInputHigh(D1);
+
+  keyboard_pre_init_user();
+}
+```
+
+[Changes to `keymap.c`](https://github.com/qmk/qmk_firmware/pull/8472/files#diff-05a2a344ce27e4d045fe68520ccd4771):
+- Find/Replace each instance of `#ifdef SSD1306OLED` with `#ifdef OLED_DRIVER_ENABLE`
+- The following changes are for compatibility with the OLED driver. If you don't use the OLED driver you may safely delete [this section](https://github.com/qmk/qmk_firmware/blob/e6b9980bd45c186f7360df68c24b6e05a80c10dc/keyboards/lily58/keymaps/default/keymap.c#L144-L190)
+- [Remove](https://github.com/qmk/qmk_firmware/pull/6260/files#diff-20943ea59856e9bdf3d99ecb2eee40b7L91-L158) the block
+```c
+#ifdef SSD1306OLED	
+  iota_gfx_init(!has_usb());   // turns on the display	
+#endif
+```
+- Within the block bounded by `#ifdef OLED_DRIVER_ENABLE` and `#endif // OLED_DRIVER_ENABLE`, add the following block to ensure that your two OLEDs are rotated correctly across the left and right sides:
+```c
+oled_rotation_t oled_init_user(oled_rotation_t rotation) {
+  if (!is_keyboard_master())
+    return OLED_ROTATION_180;  // flips the display 180 degrees if offhand
+  return rotation;
+}
+```
+- Remove the function `iota_gfx_task_user`

keyboards/tkc1800/config.h

@@ -67,6 +67,11 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 /* Locking resynchronize hack */
 #define LOCKING_RESYNC_ENABLE
 
+#define QMK_ESC_OUTPUT A0 // usually COL
+#define QMK_ESC_INPUT F4 // usually ROW
+#define QMK_LED D2 // NumLock on TKC1800
+//#define QMK_SPEAKER C6
+
 /*
  * Force NKRO
  *