* Rename Blockly.Blocks to Blockly.blocks
Because it does not export a type as its default export.
Part of #5073.
* Name default export of Blockly.blocks Blocks.
Use named exports in Blockly.blocks by giving the former default
export the name Blocks.
Part of #5153.
* Reexport Blockly.blocks from blockly.js
* Document the format of renamings.js better.