Alignment of buttons also on lower side

[hans23]

Hi,

for smaller displays it could be useful to add an option to align the buttons on the lower margin instead of right and/or left side.

Like this:

http://s14.postimg.org/gddbkul29/Oruxmaps_2b.jpg">



Another thing that came into my mind was that it would be nice to use the hardware buttons of the phone. So the hardware buttons have to be remapped while oruxmaps is running. But it sounds to be extensive to implement...