remap function included in the std library

The need for a remap() function (also called efit() in VEX) is very common in shading, and it would be appreciated if the standard library included it natively.

So far, of course, we can remap vectors or floats by simply defining the function manually:

```c
vector vectorRemap(vector input, vector minIn, vector maxIn, vector minOut, vector maxOut) {
return minOut + (input - minIn) * (maxOut - minOut) / (maxIn - minIn);
}
```

```c
float floatRemap(float input, float minIn, float maxIn, float minOut, float maxOut) {
return minOut + (input - minIn) * (maxOut - minOut) / (maxIn - minIn);
}
```
But, having it part of the std would simplify code and ensure a proper implementation:

```c
type remap(type input, type minIn, type maxIn, type minOut, type maxOut)
```

No files, tests, or entry points are identified in the issue, so begin by locating the standard-library implementation and existing scalar/vector utility tests. Define the supported types and edge-case behavior for remap(), then add coverage showing that the function is available and produces the expected mapped values.

Written by the indexing model from the issue text.