Cosmetic code style refactoring: add enum for screen orientation & define for OLED state

[ia]

• Please check if the PR fulfills these requirements

• The changes have been tested locally
• There are no breaking changes

• What kind of change does this PR introduce?
  Cosmetic code style refactoring. Main changes:

  • add enum for screen orientation
  • add define for OLED state
  • add markings for #endifs in files which have been updated due to implemented refactoring
  • plus some intuitive unification including following non-formal rules such as:
    • add empty new line between blocks of function/method implementations
    • remove empty new first line inside of function/method (since most functions/methods don't have it)
      And so on.

• What is the current behavior?

• What is the new behavior (if this is a feature change)?

• Other information:
  It's more like experiment than anything else and I hope I didn't mess much with preferable style but I just tried to unify code style in files which I updated anyway. Can't wait for feedback.

Made builds successfully and tested firmware on TS80P but there shouldn't be any difference since there is no any functionality update.

[Ralim]

This looks fine to me.
You really like annotating the #endif dont you? Doesnt your IDE do that for you 😁

[ia]

You really like annotating the #endif dont you?

Had a couple of problems in the past due to not having them. ;)

Doesnt your IDE do that for you 😁

Touche`! :D
Sometimes it's just super-convenient visually to have them when you only want to check something very briefly through simple editor/online code navigation.