In UI and API, include the parts of a character class as its children

[bfriesen]

So that I can better understand a character class, I want to break it down into its component parts.

Example:

[abc]
    a
    b
    c

[a-zA-Z0-9_]
    Characters from a to z
    Characters from A to Z
    Characters from 0 to 9
    _