Instead of hard-coding 22 in random places, just make the following
widgets have a fixed height of 22 by default: Button, CheckBox,
ColorInput, ComboBox, RadioButton, SpinBox, TextBox.
In the future we can make this relative to the current font size,
but for now at least this centralizes the setting a bit better.
This patch adds the ability to enable "input history" on a textbox,
allowing to navigate between the history with the arrow keys.
Also removes a custom TextBox subclass from HackStudio that added
the exact same hooks, and moves it to use the now standard ones.