Basic string and binary processing

- strings are now made of graphemes
- char is no longer a literal type
- preliminary binary support
- added implicit extraction methods for primitives
- added explicit extraction method for atoms

Nothing has been tested yet

ROADMAP.md

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+# IO
+
+All IO is event-based via callbacks.
+Driven streams such as stdin expose single-fire events for the results of functions such as "read until terminator" or "read N bytes".
+Network IO exposes repeated events such as "connect", "message", etc.