[dvbviewer] pump version to 1.9.15
[dvbviewer] add genre
[dvbviewer] minor code cleanup
[dvbviewer] don't cache recordings
[dvbviewer] cleanup timeshift api a bit

Allow fetching the TS buffer instead of wrapping all calls through
dvbdata. Additional implement GetBufferTimeStart, GetBufferTimeEnd
and GetPlayingTime.
[dvbviewer] minor cleanups in GenerateTimer
[dvbviewer] speed up timeshifting start
[dvbviewer] revert to localtime

There's no localtime_r on windows
[dvbviewer] prevent timeshift buffer from draining
[dvbviewer] use timezone offset for timers again

Turns out RS gmt offset doesn't include the daylight saving time. So
just fetch the offset on our own.
[dvbviewer] disable caching for remote URLs

Disable caching for RS URLs. We don't seek or similar stuff.
Also disables caching for local timeshift buffer. XBMC doesn't enable
this for local files, though.
[dvbviewer] fix tsbuffer length() returning a cached value

We can't use GetFileLength as it's value will be cached
by XBMC until we read or seek above the cached value.
[dvbviewer] add proper timeout to timeshift read
[dvbviewer] fix using local favourites file

additional replace a goto with while-loop
[dvbviewer] add support for grouping recordings

Allow grouping:
* by recording directory
* by recording date
* by first letter
* by tv channel
* by series
[dvbviewer] update changelog
Merge pull request #295 from manuelm/master-pull

dvbviewer: update to 1.9.15