Merge branch 'hv/config-from-blob'

Merge branch 'hv/config-from-blob'

Allow configuration data to be read from in-tree blob objects,
which would help working in a bare repository and submodule
updates.

* hv/config-from-blob:
  do not die when error in config parsing of buf occurs
  teach config --blob option to parse config from database
  config: make parsing stack struct independent from actual data source
  config: drop cf validity check in get_next_char()
  config: factor out config file stack management