Wording fixes in error messages
This PR is largely wording fixes to existing PRs that I found going back through the ones that have already been updated. Sometimes seeing the message in context made me think "oh there's a better wording!"
There's one additional fix. This will also prevent the secondary underlining of derive call (since they look like macros to the system in the way I was using):
```
error[E0184]: the trait `Copy` may not be implemented for this type; the type has a destructor
--> src/test/compile-fail/E0184.rs:11:10
|
11 | #[derive(Copy)] //~ ERROR E0184
| ^^^^
| |
| in this macro invocation
```
Is now just:
```
error[E0184]: the trait `Copy` may not be implemented for this type; the type has a destructor
--> src/test/compile-fail/E0184.rs:11:10
|
11 | #[derive(Copy)] //~ ERROR E0184
| ^^^^
```