Implement indent and offset for YAML blocks

[thorstenkampe]

Please make YAML configurations options available so that this kind of output would be possible:

---
-
  - 1
  - 2
  - 3

---
map:
  - 1
  - 2
  - 3

---
-
  key1: 1
  key2: 2
  key3: 3