Clean up the release notes.

In particular, spell out the current dynamic situation, clean up the
FIXMEs and xrefs, and don't forget to mention InterruptibleFFI.

Signed-off-by: Austin Seipp <austin@well-typed.com>
Also mention Pattern Synonyms (but with a FIXME)

Signed-off-by: Austin Seipp <austin@well-typed.com>
More release note touchups.

Signed-off-by: Austin Seipp <austin@well-typed.com>
More tweaks.

Signed-off-by: Austin Seipp <austin@well-typed.com>
Fix more 32 bit performance fallout.

Some of these are actually worse than I thought upon inspection, but
after a little digging I haven't found exactly what has caused them.
Some were certainly bitrotted, but others seem updated more recently, so
something has slipped.

I'll be filing a ticket about these.

Signed-off-by: Austin Seipp <austin@well-typed.com>