* saveSettings: add comment for #endif, update var name to reflect its purpose regardless its one-time & temporal
* Settings.h: add enum for orientation mode
* settingsGUI.cpp: add markings for #endifs, add/remove extra new lines to propose better code read-ability in my humble vision from the side, didnt touch any functionality only cosmetic syntax
* settingsGUI.cpp: remove added-by-accident new line in the end of the file
* OLED.hpp: unify ifdef section, add markings for #endifs, add readable macros for ON/OFF OLED state instead of magic numbers
* OLED.cpp: add markings for #endifs, add readable macros for ON/OFF OLED state instead of magic numbers, trying unify common style for the whole file for better read-ability
* Settings.cpp: unify code style
* settingsGUI.cpp: revert true/false for setDisplayRotation
* OLED.cpp: unify comments style