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.
upnpsoap: make subtitle support more generic

It sounds like more clients may support subtitles using a res element,
so we should make our support more generic.
clients: add Asus O!Play support and quirks

Asus O!Play reboots with titles longer than 23 characters with some
file types when there are subtitles present.  So we truncate video
file titles with external subtitles.

It also supports subtitles in LG fashion, so add that too.