[eval2] Don't permit tracing mincfuns with :encapsulate nil.
[eval2] Fix compilability.
[eval2] Fix a refactoring bug.
[eval2] Clean up.
[eval2] Document eval2-types.
[eval2] Document eval2-types more.
[eval2] Document the VM code.
[eval2] Improve documentation.
[eval2] Complete VM code documentation.
[eval2] Fix a documentation typo.