Run content [#19]

- [x] Add bidirectional override (a)
- [x] Add bidirectional embedding level (b)
- [x] Add content part (c)
- [x] Add control (d)
- [x] Add carriage return (e)
- [x] Add long day (f)
- [x] Add short day (g)
- [x] Add deleted text (h)
- [x] Add invalidated field cache (i)
- [x] Add phonetic guide text size (k)
- [x] Add phonetic guide base text size (l)
- [x] Add phonetic guide text size rasie (m)
- [x] Add position of last rendered page break (n)
- [x] Add language id for phonetic guide (o)
- [x] Add long month (p)
- [x] Add short month (q)
- [x] Add non-breaking hyphen (s)
- [x] Add page number block (v)
- [x] Add absolute position tab character (w)
- [x] Add phonetic guide text (x)
- [x] Add phonetic guide (y)
- [x] Add phonetic guide text alignment (z)
- [x] Add phonetic guide text base (aa)
- [x] Add phonetic guide properties (ab)
- [x] Add optional hyphen (ac)
- [x] Add tab (ad)
- [x] Add long year (ae)
- [x] Add short year (af)
It's definitely that there is always an expectation, even if it's just that the value can't be `nil`.

I used the named argument syntax for how it reads, but this definitely an internal DSL for constructing attributes.

I think I will add a guard clause to raise an exception if `expects` is `nil`.