Emitter cannot emit BigInt or BigDecimal

The reader understands BigInt and BigDecimal literals, but the emitter will throw an exception when it finds them.

I know CLJS does not have a proper number tower, but it should at least be able to accept literals like "1N" or "1.5M".

Attached is a patch which will cause the emitter to coerce BigInt and BigDecimal to double-approximations before emitting.