[analyzer] Better model for copying of array fields in implicit copy ctors.

- Find the correct region to represent the first array element when
  constructing a CXXConstructorCall.
- If the array is trivial, model the copy with a primitive load/store.
- Don't warn about the "uninitialized" subscript in the AST -- we don't use
  the helper variable that Sema provides.

<rdar://problem/13091608>
Escape more @ signs in Doxygen comments.

Doxygen treats "@command" the same as "\command" in a doc comment, so
whenever we talk about Objective-C things like "@interface" we have to
make sure to escape them.

Let's try to keep Clang -Wdocumentation-clean!
Attempting to fix the build on older GCC versions.