Revert "delete everything" (includes everything non-go-crypto)

This reverts commit 96a3502

types/block_meta.go

@@ -0,0 +1,15 @@
+package types
+
+// BlockMeta contains meta information about a block - namely, it's ID and Header.
+type BlockMeta struct {
+	BlockID BlockID `json:"block_id"` // the block hash and partsethash
+	Header  *Header `json:"header"`   // The block's Header
+}
+
+// NewBlockMeta returns a new BlockMeta from the block and its blockParts.
+func NewBlockMeta(block *Block, blockParts *PartSet) *BlockMeta {
+	return &BlockMeta{
+		BlockID: BlockID{block.Hash(), blockParts.Header()},
+		Header:  block.Header,
+	}
+}