Add FlipX & FlipY to Cocos2d-x runtime

[shrimpz]

Add follow code to CCSkeletonAnimation.h

void setFlipX(bool t)
{
    skeleton->flipX = t;
}

void setFlipY(bool t)
{
    skeleton->flipY = t;
}

[NathanSweet]

Why not just access the skeleton directly? I'd rather not add methods to get/set the flip x/y, bones, slots, etc.

[shrimpz]

i'm sorry, i'm weak in English.

Because I use Spine in Cocos2d-x's Lua Version, if access Skeleton directly, I must wrap Skeleton to Lua, in Lua, i must write code like follow:

sa:skeleton.flipX = 1

but write follow, I needn't wrap Skeleton to Lua, and Lua Call quickly...

sa:setFlipX(true)