Feature request: Add runtime exception check instead of error "compile-time refinement only works with literals"

Hi,
I'm posting this feature request after a small e-mail exchange with @fthomas

The code

```
for (i <- -1 to 3)
println(refineMV[Positive](i))
```

currently results in _compile-time refinement only works with literals_ error.

I suggest that instead this will result in a runtime check, meaning four possible cases:
1. **Compile time check pass for literal (no runtime check required)**

```
println(refineMV[Positive](1))
```

Prints outs:
1
2. **Compile time check fail for literal**

```
println(refineMV[Positive](0))
```
3. **Compile time check could not run, so running runtime check instead, which passed**

```
for (i <- 1 to 3)
println(refineMV[Positive](i))
```

Prints outs:
1
2
3
4. **Compile time check could not run, so running runtime check instead, which failed and throws exception**

```
for (i <- -1 to 3)
println(refineMV[Positive](i)) //Throws exception
```

Note:
Instead of modifying refineMV you may wish to keep it as is, and add another flavor (something like refineMVRE [Macro Verify, Runtime Exception], or whatever acronym you wish). However, I don't think you should. Keep it simple with the least functions possible.

Thanks,
Oron

Start at the refineMV entry point named in the issue and compare its current literal-only behavior with the four examples. Done means literal checks retain compile-time behavior, non-literals use runtime validation, and failures throw an exception; no file or test path is named.

Written by the indexing model from the issue text.