bugc: compile ! as a logical not - #353

* bugc: compile `!` as a logical not

* bugc: link the changelog entry to #353

* bugc: end each source range at its last token

* bugc: link the changelog entry to #362

* bugc: add block.prevrandao

* bugc: link the changelog entries to #363

* bugc: hash several value-type words with keccak256

* bugc: link the changelog entries to #365

* bugc: slice a fixed-size bytes value by its bytes

* bugc: link the changelog entry to #357

* bugc: hash the data of dynamic bytes and strings

* bugc: link the changelog entry to #360

* bugc: give a caller's call JUMP the invoke's arguments

* bugc: list variables before a function's first statement

* bugc: store a memory string's bytes when assigning it to storage

A storage write took its value as a word, so a memory string or bytes
reference wrote its memory address into the slot. Code generation now
encodes the referenced bytes as Solidity does: inline with length * 2
up to 31 bytes, else length * 2 + 1 in the slot and the data from
keccak256(slot), with the last word's trailing bytes cleared. A slice
now carries the bytes type, so its value is recognized too.

* bugc: link the changelog entry to #355

* bugc: say why the bytes test slices without naming the copy width

* bugc: copy all of a slice's bytes

irgen built a slice's data as a read and a write, and a read or write
moves at most one word, so only the first 32 bytes were copied. Add a
copy IR instruction (CALLDATACOPY from calldata, MCOPY from memory) and
emit it for the slice's data.

* bugc: link the changelog entries to #359

* bugc: copy a struct read from storage into memory

* bugc: link the changelog entries to #361

* bugc: lay storage arrays out as Solidity does

* bugc: add push to dynamic arrays in storage