Python3 fixes
Python3 fixes

On a vim build that supports only python3 (such as the version in Debian
testing at the moment, `2:8.0.0003-1+b1`), `ocp-indent-vim` fails: it
always indents to 0 spaces.

This is because of a compatibility problem of the `ocpindent` python
module with python 3:

- pipes work on bytes, not strings, so it is necessary to `encode()` the
  `content` variable.
- `map` returns an iterator instead of a list, so it has no `pop()`
  method.

def-lkb/ocp-indent-vim