Merge branch 'refs/heads/t/long-help'

Merge branch 'refs/heads/t/long-help'

This series introduces lsu.c and lsu.h which contain helpers related to
the lopsub library. These helpers are designed to be shared between
the executables. The series starts by implementing a generic help
command for lopsub suites and converts para_server. Subsequent patches
convert audiod and para_play.

The second part of the series adds another lopsub related helper which
merges command line options and config file options. Each executable
is modified to make use of the new helper, getting rid of quite some
code duplication.

The conflict resolution for server.c has been tested for a while.

Cooking for five weeks.

* refs/heads/t/long-help:
  play: Use lsu_merge_config_file_options().
  mixer: Use lsu_merge_config_file_options().
  gui: Use lsu_merge_config_file_options().
  filter: Use lsu_merge_config_file_options().
  audioc: Use lsu_merge_config_file_options().
  audiod: Use lsu_merge_config_file_options().
  client: Use lsu_merge_config_file_options().
  lsu: Add helper to merge config file options, convert server.
  Trivial: Rename completion_result variables.
  play: Implement help --long.
  audiod: Implement help --long.
  Introduce lsu.{c,h}, implement help --long for para_server.