More conditional and loop snippets

[EmilyGraceSeville7cf]

• snippets for comparisons in if and while
• snippets for iterating over ranges and files for for
• simplify snippet names for builtins
• remove snippets for list, table and range creations as they are simple constructs to type
• use ${<number>:command ...} instead of ${<number>:block} and ${<number>:closure}

[fdncred]

Good to see you back. Thanks!

[fdncred]

Can you add a def --wrapped in the same manner that you just changed def --env? If we can get that in, I'll land this.

[EmilyGraceSeville7cf]

Done. :)