Implement css FlexBox

[Alex2772]

At this point, AText is used to mimic flex box functionality because it accepts views in it, and can act as a layout. We need to extend its API with css's flex functionality

API mock up

class AText {
....
struct FlexParams {
AlignContent alignContent = AlignContent::NORMAL;
JustifyContent justifyContent = JustifyContent::NORMAL;
AlignItems alignItems = ALignItems::NORMAL;
// int gap = 0 // not required, implemented by LayoutSpacing
FlexWrap flexWrap;
};

void setFlex(FlexParams params);
};

Possible implementation

• either extend AWordWrappingEngine
• either steal facebook's flex box c++ library