Allow wrap attributes for enums

Before this change, C++ attributes placed after enum identifiers would cause a syntax error for the wrapper tools. This would have blocked the ability to add deprecation markers to enum constants.

This change also enables VTK_WRAPEXCLUDE for enum types, and partially implements deprecation checks for enums in the wrappers. The "partial" implementation simply adds comments to the generated wrapper code to indicate what enum types and constants were marked as deprecated in the C++ headers.

Addendum: this MR has been amended to allow attributes to occur after the template-head in template declarations.