More portable Makefile for Mac, and fix a Mac linker difference

Quick fixes for Linux and GCC on x86_64

Adjust remarks on performance

Add Darwin arm64 support - now working on M1 Macs!

Rebuild DO LOOP and friends to keep the loop index in a register

Add `>NAME` which given an XT tries to find its NT (name token)

Fix `WORD`, which is supposed to skip leading delimiters

Make `'` and `[']` report an error if they can't find the word

Increase the dictionary size to 64MB

Add [IF] [ELSE] [THEN] with tests

Add REGISTERS flag to allow forcing globals rather than pinned registers

Add support for relative REQUIRE ./some/path

Fix ccall primitives to take the function last, as originally intended

Fix SP@, which fixes PICK and ROLL

x86_64: Tweak register assignment to not use %rbp