Revert "Make terminal font size pixel based"

This reverts commit 0b1a366126766bf61dae7a36cd375d9cf33554a6.
Revert "fix the menu font size changer after last"

This reverts commit 221d69ec3a7dfb2c2f7587e0575e45c50ad92fc5.
Implement text font size rounding (same as in QtQuick Text, hopefully)