cerealization
Document capnp tool and constants.
Fix sidebar alignment for new logo.
Doc updates.
More doc updates.
News post for 0.3 (getting it ready early).
Fix dist.
Fix test.
Fix bug when schema validation fails with -fno-exceptions.
Fix obscure bug where allocating an empty struct causes trouble.  For reasons I don't yet fully understand, this actually caused a crash on 32-bit OSX builds (but not 64-bit, nor 32-bit Linux).
Actually fix the bug, which was a doozy:  OrphanBuilder::tag was sometimes initialized using WirePointer::setKindAndTarget(), but since the tag didn't live inside the target segment, this used illegal pointer arithmetic.  The target is never read from an orphan tag anyway, so I thought it would be no big deal.  But it turns out Clang actually optimizes under the assumption that pointer arithmetic returns a whole value.  As a result, on 32-bit system where 64-bit values are only 32-bit aligned, the tag and target might not have been a whole number of words apart, and the extra bit actually found its way into the 'kind' bits, causing e.g. a struct pointer to become an invalid far pointer.  Crash.  The fix required refactoring to ensure that setKindAndOffset() is never used for orphan tags.