Add unit selection menu
It would be more user friendly if user can input frequency without conversion(mostly MHz). But in #4981 (closed) we see that in some cases tunning frequencies need the full Hz resolution and adding small menu besides frequency field would enable that.
This is from linuxtv wiki:
Transponder Frequency as Integer
DVB-S
Frequency in MHz.
DVB-C
Frequency in MHz, kHz or Hz.
DVB-T
Frequency in MHz, kHz or Hz.
analogue TV
Frequency in MHz. (analogTV plugin)
The values here will be multiplied by 1000 until it's bigger than 1000000.