Cut down on the noise that easage-list generates

[phrohdoh]

easage list is quite noisy at the moment.

Planned changes:

• [ ] Introduce a --verbose flag
• [ ] Output only entry names if the verbose flag is not present
• [ ] Output the currently-outputted information if the verbose flag is present

For reference this is what easage list currently produces on a test BIG archive I have locally:

Archive:
  kind: BigF
  size: 218
  len: 2
  data start: 0x36
Entries:
  test/b.txt
    offset: 0x36
    len: 20
  test/a.txt
    offset: 0x4a
    len: 144