added ok, cancel buttons, started with menu
added menu class
continued on MenuTest
added menu navigation functions
Linking menu to display (still ongoing)
Minor bugfixes in menu
Introduced sub_menu structure
added debug information
still analyzing push/pop-problem
Menu working

replaced StackArray with pointer to parent SubMenu, replaced structs by
objects (SubMenu, MenuItem)
removed StackArray include
Initialize-Function from menu
added timed mode
message for end of timed mode
menu progress bar
Changed digital pin 10 to 11
I2C LED bargraph
Buttons can be kept pressed for setting numbers
Added camera trigger sketch
Merge branch 'menu'