[*] StbMainApp: Add DVB tuner caps
[+] StbMainApp: Add support for several installed DVB tuners

appControlInfo.dvbInfo.tuner indicates current selected tuner,
index of appControlInfo.tunerInfo[].
appControlInfo.tunerInfo[].adapter points to either dvbInstance[] in dvb.c,
or virtual ST tuner (it's index is st_getTunerIndex(tuner)).