Create fn-type which forces flow

[kkinnear]

Let people configure this:

(:require
  [boot-fmt.impl :as impl]
  [boot.core :as bc]
  [boot.util :as bu])

[kkinnear]

Fixed in 0.2.10.

Two new function types: :flow and :flow-body, each of which will never allow the function which has this type to print on the same line or even hang -- it will always put the first argument (or body form or whatever) on the next line indented by whatever indent you have configured for arguments or body forms.