add "setStyle" expression in texts

[Saariko2]

setStyle(styleObject, from, length)

this function will go over all the supported properties of the style object and set them to the target style.

thus we will not need to get the fontSize, fontColor, font, etc... from the source style and apply them with setFontSize, setFillColor, setFont, etc... to the target style. it will be avilable in a single expression function