Allow hash values delimited by \n inside of {}

This allows for syntax such as:

some_hash = {
  :foo => 'bar'
  :bar => 'foo'
}
Reduce assocs_no_comma rules, add assoc_seperator
Add support for Ruby 1.9 style symbol hashes

Credit goes to nobu for this patch
(https://bugs.ruby-lang.org/issues/8956#note-2).
Allow array members delimited by \n inside []

This allows for syntax similar to the modified hash syntax, e.g. (rather
complex example):

    some_array = [
      :foo
      :bar
      [
        'baz'
        :qux
      ]
      {
        :quux => 'grault'
        'garply' => [
          'waldo' => :fred
        ]
        :plugh => 'xyzzy'
      }
    ]
Rename assoc_seperator -> nl_or_comma

Now that I've added support for arrays, the name "assoc_seperator" is
somewhat misleading since this rule now also applies to aref_args.
Add support for method arguments

This enables syntax such as

    Hash[
      :foo, 'bar'
      :baz, 'qux'
    ]

(becomes `{ :foo => "bar", :baz => "qux" }`)

as well as

    puts("this is line one"
         "this is line two"
         "this is line three")
Replace optional nl_or_comma with trailer
Tests for no-comma hashes, arrays, and method args