Escape code 1049l clears terminal output when Ion used as Intellij Idea terminal's shell

There's an issue with Ion shell being used inside Intellij Idea's terminal: after every command output is cleared. The more verbose description is in the comments of Idea's bug tracker: https://youtrack.jetbrains.com/issue/IDEA-215394

adminxvii from Redox team's chat identified it is an addition of 1049l escape code in editor.rs that causes the problem. I verified that removing it fixes the bug with the shell; however, I do not know if other escape codes on that line (1000l and 1l) make sense without 1049l, so maybe they should be removed as well in case they don't.

The reason for an addition of those escape codes was fixing Vim's problem with improper exit, and I haven't tested if it reintroduces the problem since I'm not sure of the exact details.