added Texture.fromFileName

shortcut to load a texture directly from filesystem
extended TextField functionalities

extended font and text support in textfields
Changed getSize/getWidth/getHeight logic [break]

- breaking changes in getSize/getWidth/getHeight. From now on this
methods accept a targetSpace, with default value on self (so getSize()
-> return the width, height in local space)
- Changed logic for inheritance linking (using of clear/setAttrLink)