Update grammar and snippets

[dcodeIO]

• Remove no longer valid instructions
• Support all current instructions, incl. experimental ones in the wild
• Support non-standard Binaryen extensions in its s-expr format
• Recognize ids as of the spec
• Recognize ids referring to a function name
• Add floating point literals
• Fix whitespace
• Fix snippet warnings

Still not perfect and probably the most horrible PR diff I've proposed in a while. Would totally understand if that's not a PR you are comfortable with, yet didn't know what else to do with all of this.

Is this something you'd consider?

[syrusakbary]

The PR looks good. The change on whitespaces makes it a bit harder to follow up, but I think it should be ok.

Let me know once is ready to review :)

[dcodeIO]

Ok, great! I think it's good for reviewing. What I'm unsure about are the pattern names like storage.type.wat and so on. Some sources say so, others say so.