upgraded to libgit2 v0.21.1
re-added brackets
welcome Git::Internal::Buffer
use Git::Internal::Buffer and deprecate methods without Git::Result
added toString() to Git::Internal::Buffer

Note: defaults to QString::fromUtf8() when no text codec is set.
using the new method Buffer::toString() for path lookup in Git::Config
added docs
use utf-8 encoding for pathes
fixup commit
cleanup