#514 Introduce column breaking in tof/menubutton

[Andras Muranyi]

Problem:
When adding many elements to the menubutton, only a single column is created and when that reaches the edge of the screen new elements will appear off-screen.
Solution:
Break the menu into new columns using the COLUMNBREAK constant.
Solution adapted from the column breaking mechanism in tof/pmenu (not working as is, fixed by patch #512).