Bump Scala version, break `inlineAndReset`.

Time to get back at this :)

So yeah, about `resetAllAttrs`:

> 31) Removal of resetAllAttrs. resetAllAttrs is a very dangerous API and shouldn’t have been exposed in the first place. That’s why we have removed it without going through a deprecation cycle. There is however a publicly available replacement called resetLocalAttrs that should be sufficient in almost all cases, and we recommend using it instead.

Compiler also has the following to say about `resetLocalAttrs`:

> method resetLocalAttrs in trait Typers is deprecated: Use `c.untypecheck` instead

Unfortunately, neither of those work with single triangle example, :

> scala.reflect.internal.FatalError: symbol value acc does not exist in org.macrogl.examples.SingleTriangle.main

I'll be looking into this issue tomorrow, but since you may already know how to fix it, I'm posting it here.