Introduce a new mode to generate only flipped rules

[elchininet]

The new diff mode allows to generate the minimum amount of code because it only outputs the rules that have been flipped and without prefixing them. The intention of this method is to generate a separate stylesheet file that will be loaded on top of the original one to override those rules that need to be flipped in certain direction.

Note: This method has the same disadvantage of using the override method.

Input

.test1, .test2 {
    background-color: #FFF;
    background-position: 10px 20px;
    border-radius: 0 2px 0 8px;
    color: #666;
    padding-right: 20px;
    text-align: left;
    transform: translate(-50%, 50%);
    width: 100%;
}

.test3 {
    direction: ltr;
    margin: 1px 2px 3px;
    padding: 10px 20px;
    text-align: center;
}

Output

.test1, .test2 {
    border-radius: 2px 0 8px 0;
    padding-right: 0;
    padding-left: 20px;
    text-align: right;
    transform: translate(50%, 50%);
}

.test3 {
    direction: rtl;
}