Meter now treats 5/* as flat.

Before Meter would treat 5/* as either 3/* + 2/* or 2/* + 3/*. Treating 5/* as
a flat sequence of 1/* nodes gives better results during rewriting in most
real-world situations.

Also improved meter-node subdivision. Nodes representing beats greater than an
eighth-note in length are automatically subdivided into 2 parts, while nodes of
an eighth-note in length are subdivided into 4 parts. This prevents rhythms
like the following from appearing:

    { c'32 d'32 ~ d'32 e'32 }

That would now be rendered as:

    { c'32 d'16 e'32 }

... which is simply better looking.