I was looking into fixing JuliaStrings#15 but realized that the special casing of `InlineString1` to only have one byte makes that not work. I would say that the current special casing of `InlineString1` creates quite a bit of confusing behavior:

```
julia> InlineString("") |> typeof
String3

julia> InlineString("a") |> typeof
String1
```

Why would an empty string take more place than a one letter string?

```

julia> String1("")
ERROR: ArgumentError: string too large (0) to convert to String1
Stacktrace:
 [1] stringtoolong(T::Type, n::Int64)
   @ InlineStrings ~/.julia/packages/InlineStrings/xUsry/src/InlineStrings.jl:321
 [2] String1(x::String)
   @ InlineStrings ~/.julia/packages/InlineStrings/xUsry/src/InlineStrings.jl:208
 [3] top-level scope
   @ REPL[4]:1

julia> String3("")
""
```

Wut?

There is nothing in the documentation that indicates this type of special behavior.

I'm sure there is some reason for doing this since so much pain seems to have been gone through to do it but I thought I would put up this PR nonetheless.

Fixes JuliaStrings#73
Fixes JuliaStrings#72