Build error when using certain method names

Example benchmark method:

```cs
[Benchmark] public void System() { }
```

Fails with

```
error CS0119: 'Benchmarks.System()' is a method, which is not valid in the given context
```

We should use `base.MethodName` for instance methods, or `<FullyQualifiedTypeName>.MethodName` for static methods, rather than the simple `MethodName`. And qualify all types with `global::`