Complete theming #76

Any chance you can add additional theming elements, such as symbolIcon.* and debugTokenExpression.* to the themes? For example, something like the following for debug tokes in Github Dark would give the theme a more complete feel:

"debugTokenExpression.name": "#79b8ff", "debugTokenExpression.value": "#9ECBFF", "debugTokenExpression.string": "#9ECBFF", "debugTokenExpression.boolean": "#85E89D", "debugTokenExpression.number": "#85E89D", "debugTokenExpression.error": "#F97583",