* spec updates
* make several constants uint64 to help minimize casting
* document data type woes - will have to revisit these
* change comment style on fields and constants to make room for better
comments
* add BLSVerify and BLSAddPbkeys facades to insulate spec code from
milagro
* fix proof of possession type
* drop explicitly ordered container fields from ssz - there's an issue
open to sort this out before committing it to the spec
* more work on block processing
* fix some unsigned issues
* fix ssz issue when last chunk is not full
* work around empty const seq compiler bug
* XXX -> TODO
* rename from tree_ssz
* add special cases for some types based on beacon chain code
* add smoke test
* avoids some trivial allocations, but the big one remains - the
temporary
chunk buffer is still heap allocated
* update to handle zero-length buffer case same as latest spec
* first part of spec updating; some constants, structure changes, data type changes from int to uint
* Update beacon_chain/datatypes.nim
Co-Authored-By: tersec <tersec@users.noreply.github.com>