Merge adjustments:
- Preserved original `base_type_no_ref` argument type as ::TypeTag
- Removed superfluous #pragma guard around deprecated TableVal ctor
- Clarify NEWS regarding MetaHook{Pre,Post} deprecations
- Simplify some `::zeek::` qualifications to just `zeek::`
- Prefixed FORWARD_DECLARE_NAMESPACED macro with ZEEK_
* origin/topic/timw/266-namespaces:
Disable some deprecation diagnostics for GCC
Rename BroType to Type
Update NEWS
Review cleanup
Move Type types to zeek namespace
Move Flare/Pipe from the bro namespace to zeek::detail
Move Attr to the zeek::detail namespace
Move Trigger into the zeek::detail namespace
Move ID to the zeek::detail namespace
Move Anon.h into zeek::detail namespace
Mark all of the aliased classes in plugin/Plugin.h deprecated, and fix all of the plugins that were using them
Move all of the base plugin classes into the zeek::plugin namespace
Expr: move all classes into zeek::detail
Stmt: move Stmt classes into zeek::detail namespace
Add utility macro for creating namespaced aliases for classes
