auto clip long data

[panyanyany]

there are 3 kind of long data：

• long text (as screenshot shows)
• long item list as direct children
• long nested item list

these data would boring your eyes. but it's hard to determine what items should be hidden and how to hide them.

some way have come up to my mind:

for long item list

1. merge same-prefix item into one item, such as:
   1. f_code, f_back, f_locals in frame object
      we could represent it as:

    object(frame):
      f_back: .....
      f_code: ....
      f_*: 4 hidden items