Option to disable wasmbind feature to prevent wasm interface polution

[8e8b2c]

I'm using typeshare with a project that builds a wasm module that must conform to a specific interface. Once I add the typeshare crate to my dependencies for the purpose of annotating my types, my wasm module's exports become tainted:

Compile(\"Error while importing \\\"__wbindgen_placeholder__\\\".\\\"__wbindgen_describe\\\": unknown import. Expected Function(FunctionType { params: [I32], results: [] })\") }), wasm_trace: [] }))"))

The culprit appears to be the wasmbind feature on chrono.

I have a fix/workaround that's easy enough: make wasmbind an optional but default feature. I'll open a PR shortly.