How do I distinguish paths by group in multiple group models?

By default, `umxRAM` labels paths using s simple "A_to_B" style.
To distinguish what group a path is in, simply add `suffix = ` to the `uxmRAM` call. This will add the suffix string to each path. (for one-off differences, just add the label manually inside `umxPath`).

so

```
m1 = umxRAM("firstGroup", data=data, suffix = "_group1",
umxPath(v.m. = c("A", "B")),
umxPath('A', with = 'B')
)
```
Would contain paths like "A_with_B_group1"