Use type aliases for <eventcopy> and <errorcopy> definitions

[eduardosm]

Reduces the amount of parse and serialize code.

[psychon]

Wow, that gets rid of lots of code.

It means that the Debug implementations now sometimes print the wrong type name, but I guess that's something people have to live with. The context should make it clear which kind of event/error they actually have.

[psychon]

I was curious. Just the last commit has this stat:

 5 files changed, 1258 insertions(+), 5543 deletions(-)