[gui] adds listitem info label inprogress to determine if epg item is in progress

This adds a new listitem info label inprogress which indicates if the
associated epg tag points to a current ongoing program.
Added Container.IsUpdating
jsonrpc: expose specialsortseason and specialsortepisode for episodes
dvdplayer input stream: fix incorrectly set of EOF
paplayer: proper handling of non seekable streams
[builtins] PlayMedia() should use a sort order appropriate for the items. fixes #15136
FIX: [droid] crash when stat'ing /mnt/secure/asec on some devices (fixes #15148)
upnp: fix sort by upnp:rating
upnp: ignore "Unknown" as a single genre as it is added by Platinum
CDateTime: extend SetFromW3CDate() and add GetAsW3CDate(), GetAsW3CDateTime() and SetFromW3CDateTime()
upnp: fix serialization/deserialization of datetime properties
move ISliderCallback into its own header file
guilib: don't abuse and redeclare SPIN_CONTROL_TYPE_FOO
CGUISliderControl: fix SetIntValue() and SetFloatValue()
upnp: add some potentially useful logging to CUPnPPlayer::PlayFile()
Merge pull request #4594 from FernetMenta/paplayer

paplayer: proper handling of non seekable streams
Merge pull request #4607 from koying/fixdroidstoragecrash

FIX: [droid] crash when stat'ing /mnt/secure/asec on some devices (fixes #15148)
[osx] fix make build on osx
[tests] fix CharsetConverter.utf8To_UTF32LE test on osx
[tests] fix HttpHeader test