Spelling of „Executor“

[knothed]

Throughout the code, „Executor“ is incorrectly spelled „Executer“. For example, here, the files and folder names, and consequently the class names, are spelled incorrectly.

[mrylmz]

There are no references left which are using the spelling Executor. I think the Executer is the correct spelling to use here.

[knothed]

There are still directories called "Executor".

I think both spellings are correct for this use-case, but since all of the code uses "Executer", the directories should be adapted accordingly.