Allow paren expressions in if etc

[rattrayalex]

Allows if (a > b) and (b > c): blah()
Disallows if (cond)result (there must be a space after the paren). This resolves ambiguities.

Expected addition to the docs:

One-line syntax with parens

While the colon syntax above is recommended, traditional styles work as well.
However, when using parens around the clauses of if, switch, with, and while,
and the body is not a block, the closing paren must be followed by whitespace.

Eg; these are legal:

if (x > 1) return

if (x > 1){
  return
}

but this is not:

if (x > 1)return

[wcjohnson]

Tested this against a code base I'm working on, no regressions. Edge cases look pretty far fetched. Looks good as far as I can see.

[rattrayalex]

Cool, thanks!