Include using full relative path

[mickeprag]

This is needed by Arduino since it is not yet supported to specify
include directories manually

Fixes #185

[martinberlin]

@Yardie- can you please test Micke's branch and add it as an Arduino library?

I think the issue with Arduino IDE is that it expects all header includes without relative paths.

Please note that in my comment on Slack I mentioned without relative paths (Not with relative paths). Please read this as a reference.
I just tried to build the dragon example in IDF after this update and it still works. Now when I try to add a symlink to this branch in Arduino libraries:

martin@martin-IdeaPad:~/snap/arduino/current/Arduino/libraries/epdiy$ ln -s /home/martin/esp/projects/pull-requests/epdiy-micke epdiy

I see it coming and have an example also in Arduino, that I have latest version in Ubuntu installed using Snap (check patch), when I try to build it I get:

   from /home/martin/snap/arduino/current/Arduino/libraries/epdiy/src/epd_driver/i2s_data_bus_s2.c:1:
/home/martin/snap/arduino/61/.arduino15/packages/esp32/hardware/esp32/2.0.2/tools/sdk/esp32/include/soc/esp32/include/soc/rtc.h:16:21: error: #include nested too deeply
 #include <stdbool.h>
                     ^
/home/martin/snap/arduino/61/.arduino15/packages/esp32/hardware/esp32/2.0.2/tools/sdk/esp32/include/soc/esp32/include/soc/rtc.h:17:20: error: #include nested too deeply
 #include <stddef.h>
                    ^

Like if Arduino is struggling with the include levels...Arghh...well I really don't use this IDE, other than for quick tries on other boards than ESP32. So I'm quite lost to test this. Can you please give it a try?

Micke I think we should also base this update in Valentin's idea to do this that you can see in the actual repository (Ex. epd_board.h)

[martinberlin]

Approving this after Gregory testing in Slack