GroupExport should have good defaults

**Is your feature request related to a problem? Please describe.**
Marking a class for export requires a lot of fiddly config bits.

**Describe the solution you'd like**
Add FIRST and LAST as out-alias options. Then default to:
* Export out-aliases FIRST
* Canonical ONLY_IF_NO_OUT_ALIAS
Some version of this is almost always what is wanted. If there is an out-alias, its purpose is to be exported, so export it and in that case don't export the canonical name. If there are multiple out-aliases, defaulting the first one gives an easy way to differentiate which one ends up in the auto-export.

This will not affect any existing usages because previously there were no defaults, so each export usage is explicitly specified.