csync: Move auth callback to a common struct.
csync: Add support for a log callback.
csync: Add option to set and get log verbosity.
csync: Add a new logging system.
client: Add setting the debug level.
statedb: Log an error if we can't open the database.
cmake: Get rid of log4c.
doc: Remove all references to log4c.
tests: Add a csync_log test.
tests: Remove the right directory in the teardown function.
modules: Fix csync_sftp module license header.
modules: Remove csync_sftp2 module.
modules: Fix csync_smb module license header.
modules: Fix csync_owncloud module license header.
modules: Fix csync_dummy modules license header.
std: Add missing copyright header for c_dir.c.
log: Use a thread local variable for the log level.
priv: Remove log_verbosity variable.
log: Use a thread local variable for logging callback.
std: Add discard_const macros.