Add setting for text color when inputting text

[dshepsis]

Right now, when you double click an editable text field (e.g. a comment or the name of a node), the text in that field is always black, or white when highlighted with a blue highlight. This is an issue when setting the Memory View Background Color to a dark color. These colors, at least the default black text color, should be change-able in the user-settings. This will allow users to ensure sufficient contrast even when using a "dark-mode" color scheme.

[ArcticSlayy]

Use this: #247