Normative: Change default function length value to not include option…

…al arguments.

Fixes #264.

 - A few legacy methods that have deviating lengths are documented explicitly.
 - Any unneeded explicit lengths are removed.
 - Needed legacy explicit lengths are added.
 - Spacing inside optional argument brackets is made consistent
 - Fixed a bug with a `DataView` note having the wrong argument name

The DataView prototype get/set methods have inconsistent lengths across all browsers, so rather than select one of them as legacy, I decided to let them fall into the default category, which hopefully implementations will align with.