Byte surgery on the CVM
Convex 0.8.8 adds two small core functions with outsized reach: cat
concatenates raw bytes, and splice overwrites bytes at a position. On
most platforms these would be mundane. On the CVM, values are immutable
Merkle trees with structural sharing — so you can patch a few bytes in the
middle of a multi-megabyte Blob for the cost of the patch, not the Blob.
