try to ensure proper ownership of db_dir

If user has been set, try to ensure that db_dir is owned by that user.
If that fails, log an error.
cosmetic: whitespace cleanup
process: make max number of children (connections) configurable

At least some Panasonic clients try to open more than 5 simultaneous
connections to the server.  If we keep the default of 5 max children,
it results in choppy playback on those clients.

Make this setting configurable, and default to 50 max connections.
Our process is pretty lightweight, so 50 children should not be a
problem on most systems.
print usage and bail if the user gives an unknown command line option
ssdp: improve debug logging
Wrap up version 1.1.2.
cleanup: remove unused tagutils code, and switch to standard int types
log: enhance setting loglevels

Enable logging level settings such as 'log_level=error' to set all
levels to error, or 'log_level=error,ssdp=maxdebug' to override only one
category
samsung: fix root_container setting

Pretend that we don't support SamsungGetFeatureList if we have a
custom root container specified, or else the Samsung client will
jump straight to our normal A/V/P sections.
portability: rework inline functions for clang compatibility.
Fix Clang compiler warnings.
portability: fix compiling on systems without iconv
autoconf: Use subdir-objects, to silence warnings from new autotools
clients: separate Samsung BDP and TV client types again

Advertising the DCM10 vendor-specific feature to Samsung Series
C and D (at least) players causes them to always browse ContainerID
1, no matter which section is chosen from their GUI.

Treat TVs and BDPs as separate client types with unique features.
config: introduce strtobool() helper.
config: add merge_media_dirs option

By default, if there are multiple media directories specified, there
will be entries for each one in the root directory container.  If
there is only one media directory specified, then just its contents
will be in the root container, to save one level of browsing.

Setting this option changes the default behavior so that multiple
media dirs will behave like a single media dir.