totalSizeInWords() method on generated struct readers/builders returns total size of the struct, not counting far pointer overhead.  Useful for allocating space for a flat copy.  Also a couple misc tweaks.
Don't trust trusted messages so much.  Just trust that the pointers are valid and in-bounds, but don't assume the data matches the schema.  This makes it easier to safely create a 'trusted' message: just copy any message into a MessageBuilder, and if it ends up all in one segment, it's safe to use.
Rename 'trusted' messages to 'unchecked', since they don't have to be quite so trusted anymore.
Gracefully handle the case where the schema contains types from a newer version of Cap'n Proto that we don't know about yet.
ARRRRGHHHH, these files should have been part of an earlier commit.