~cdv/loxen

Add rust to builds
[relox] Variables
[relox] Many changes, notably, strings.
[relox] Arithmetic expression parsing
[relox] start relox, Rusty Lox
[builds] Test both optimized and unoptimized builds.
[cdvlox] Add NAN boxed implementation of value.
Add NAN_BOXING option
Remove field selection from values.
[cdvlox] demacroify

They are by and large, unnecessary.
[cdvlox] Use and over mod for bitmask.
[cdvlox] optimize superclass calls.
[cdvlox] remove old build

It's really not necessary.
[cdvlox] super calls
[cdvlox] Add method invocation
[cdvlox] disable chap27 tests
[cdvlox] Add initializers
[cdvlox] add init string, lookup for init methods
[cdvlox] forbid this outside of methods.
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