Discard bed temp if none reported

[easytarget]

Very simple modification to drop the bed temperature if it is reported as 0, I've got two printers, one unheated, and got bored at seeing the zero in the display.

I think this looks OK, I simply centre the tool temp when it is the only one displaying, it is also dropped in the web display.

[Qrome]

I like this though both my printers have the heated bed. I think this fits well. Thank you. I will include it in v2.5