Create VStar expression Language for:
- Places where numbers can be input, permitting e.g. JD: 245321+3250
- Filters (includes boolean expressions over observation fields)
- Model creation (e.g. f(t) = if obscode == "FOO" then foobias + c1cos(2pi*t) ... else ...
The interpreter would have entry points for simple numeric expressions, boolean expressions, model creation expressions etc.