Remove YAX prefix from classes and namespace about yaxlib

[asbjornu]

I've pushed a branch that tries to tackle this issue, but I'm not sure about the details of all the changes you'd like to see implemented. Please have a look at asbjornu/YAXLib@f857bc202b and the api-enhancements branch and let me know what you think about the things I've done so far.

For example, I'm unsure about how to name YAXException and YAXBaseAttribute classes. They're both base classes and both have a high risk of collision. Currently, I've called them YaxException and YaxAttribute. I'm also unsure about the naming of YAXSerializer and have so far named it Serializer, but since it's a central part of the API and also has a chance of collision (or confusion), I'm thinking it should be named YaxSerializer.

It's possible to discuss these things within the commits themselves, so we can continue the discussion about specifics there if you'd like, I just wanted to bring this to your attention.

[axunonb]

@NKnusperer @304NotModified
I mean, YAX... is awkward to type and not following conventions. But it's also not just as simple as "removing the YAX prefix", like @asbjornu pointed out correctly.
Still: If we don't include the renaming of classes in v3, we should close the issue after 9 years.

[NKnusperer]

Personally, typing YAX is no issue and it makes every type name unique by default, which is a nice feature.
I would opt to close this issue too.