* Google changed from an Inc to an LLC.
This happened back in 2017 but we didn’t notice. Officially we should update files from Inc to LLC when they are changed as part of regular edits, but this is a nightmare to remember for the next decade.
* Remove project description/titles from licenses
This is no longer part of Google’s header requirements. Our existing descriptions were useless (“Visual Blocks Editor”) or grossly obselete (“Visual Blocks Language”).
* License no longer requires URL.
* Fix license regexps.
* Break CSS into modules.
Drops the compile test by 3 KB.
Remove obsolete .blocklyDraggable class stub (it used to be dynamically changed).
Remove unused menuseparator CSS.
Random improvements to require statements.
Removal of some obviously dead CSS.
.blocklyDropDownDiv no longer supresses text selection (see comment in PR).
This PR drops the compiled size by 4 KB, which is larger than I was expecting.
