使用Flexbox布局时，css解析有问题

[JohnWong]

问题

<View css="{justify-content='space-between'}"></View>

这样的写法，会报错：

space_between isn't a valid key in valid Dic {
    center = 1;
    "flex-end" = 2;
    "flex-start" = 0;
    "space-around" = 4;
    "space-between" = 3;
}

原因

原因是对css的解析不严谨，将css字符串整体将-替换为_，之后对css属性替换回来，值没有替换回来。

elseif (_v.name == "css") then
    _v.value = _gsub(_v.value, "-","_")
    local paramFun = sys:loadstring("return " .. _v.value)
    local t = paramFun()
    local css = ""
    for _k, _v in pairs(t) do
        _k = _gsub(_k, "_","-")
        if (_find(_k, "margin")) then
            css = css .. _k .. ":" .. _v*sys.scale .. ","
        else
            css = css .. _k .. ":" .. _v .. ","
        end
    end

https://github.com/alibaba/LuaViewSDK/blob/master/IOS/luaviewEx/luaviewEx/Assets/kit/pica.lua#L180