Display unit scores inside score edition tab

* This PR is relative to the first feature in #7: it displays unit scores inside score edition tab
* I have introduced 2 compound components, one for NumberPickers, one for SegmentedControls. Each of them define the label, the unit score and the control
* I have used RelativeLayouts instead of nested LinearLayouts
* I tried to do as less changes as possible

Of course, feel free to change or redesign anything.

Sylvain