+ Change +format-type to +format-region-p (now a boolean)
+ Add PRESERVE-INDENT-P boolean argument to +format-buffer
+ Add +format-preserve-indentation variable (only controls indent
preservation during +format/buffer, not +format/region, where it's
always enabled).
+ Fix error arising from +format|buffer hook when no formatter is
defined for the current mode #893
+ Change +format|buffer to alias for +format/buffer.