sharp-colon reader isn't needed to be included in cl21-standard-syntax.
Add drop, take-while and drop-while.
Remove range.
Add `1..' and `0..'. (ex. (1.. 5) => '(1 2 3 4 5))
Stop using getf for standard-object.
Delete deprecated symbols except remove-if-not.
Stop redefining nth & nthcdr. Use `elt'.
Stop using square brackets for a shorthand of getf.
Unregister the existing readtable before redefining it in use-package.
Add cl21.abbr.
Include trivial-gray-streams.