Core words

These words follow Inner core words, but unlike them, these are
self-bootstrapping and don't depend on the Cross Compiler. They
will typically be included in source form right after a stage1
binary which will interpret it on boot and bootstrap itself to
a full intepreter, which can then be relinked with the
Relinker. There is no loader for these libraries because you
will typically XPACK (B267) them.

422 core                       438 print
442 fmt                        447 readln
453 blk