Provide a nicer experience for common queries

This PR implements the features discussed in #43.

These tasks are planned for this PR, introducing `ReflectionElementExtensions`:
- [x] Accept{T}(this IEnumerable{IReflectionElement}, IReflectionVisitor{T})
- [ ] GetPropertiesAndFields(BindingFlags) - simplifies querying for properties and fields at the same time.
- [ ] GetPublicPropertiesAndFields() - includes { Public | Static | Instance }
- [ ] GetProperMethods() - gets methods excluding property accessors
- [ ] GetProperMethods(BindingFlags) - as above, with a custom filter