Digital TV: adapting the channel management UI for IPTV:

- IPTV: add individual channels
- IPTV: import m3u list of channels
- New check for remove existing channels when saving. Removes only the channels of the same type (DVB or IPTV)
- Save channels now updates the existing channels without loosing the personalization already done (for both DVB and IPTV)
- Adding channels: new counter for preventing having duplicate prefNumber channels
Digital TV: new Digital TV options, split from analog capture options

1. General
- Split menu entry into: Open Digital TV / Open Analog Capture. File->Open Device now only refers to analog device
- Split class OpenDeviceData into OpenDeviceAnalogData and OpenDeviceDigitalData
- Channel navigation panel: only enabled tabs visible (depending on Digital TV options). Set initial active tab depending
on current channel type.
- Add IGMP membership management: manage IGMP group join/leave for multicast IPTV streaming sources.
Supports only IPv4 and IGMPv2. IPv6 and IGMPv3 could be added in the future if needed.

2. Exception handling:
- error controls (checking devices, etc.) moved from the general entry point to each channel
switch operation
- Change current behavior: when error switching to channel -> show error message in info bar and ready for switch to another channel

3. Options & preferences:
- Split Digital TV options from analog capture
- New Digital TV options: DVB (BDA) and IPTV (include option: enable/disable IGMP multicast membership management)

Signed-off-by: xpc1000 <xavier_portell@hotmail.com>