[dvbviewer] pump version to 1.8.10

Start merging portisch improvements.
This requires RS >=1.25
[dvbviewer] remove signal status, fix version parsing

remove signal status. there's no api (yet)
make backend version parsing 32bit safe
additional show backend version in frontent
[dvbviewer] rename GetDeviceInfo to GetBackendVersion
[dvbviewer] more method renaming to be in line with the PVR API
[dvbviewer] use RS api to get timezone/language

additional compute and show diskspace in frontend
[dvbviewer] minor code cleanup
[dvbviewer] use generic methods for building urls to backend
[dvbviewer] rewrote recording parsing

* use imageurl + streamurl provided by the RS api
* get rid of recording port
* remove fetch image limit
* generate more unique recording ids
* some code cleanup
[dvbviewer] clean up dtor
[dvbviewer] get rid of some hungarian notation. more to follow
[dvbviewer] update delete record api url
[dvbviewer] rewrite channel + favourite list parsing

use RS api to parse both lists
[dvbviewer] make channel group creation more sane
[dvbviewer] fix possible crash

don't return pointers to (internals of) temporary variables
[dvbviewer] fix possible crash

> The parameter parmN is the identifier of the rightmost parameter in the
> variable parameter list of the function definition (the one just before
> the ...). If the parameter parmN is declared with a function, array, or
> reference type, or with a type that is not compatible with the type that
> results when passing an argument for which there is no parameter, the
> behavior is undefined.
[dvbviewer] avoid an unnecessary copy

push to vector early and use back reference for filling the object
[dvbviewer] require addon restart after changing usetimeshift/usertsp

otherwise we would need to reparse the channel list
[dvbviewer] make RTSP working

Note: RTSP is currently not compatible with timeshift
[dvbviewer] force channel sync on start

Users might switch between using RTSP/timeshift which requires new
stream urls. Changing these settings already requires a PVR restart but
this won't trigger a sync. So we now force this
[dvbviewer] fix channel index in GenerateTimer