[skins] Use classification icons instead of abbreviation

[prl]

In the EPGs and the MovieSelection screen skin (and other screens that show classification ratings), use the standard coloured classification icons instead of the SmallRating text short form, especially where the full classification text is shown available.

For example, "<PG icon> Parental Guidance Recommended" instead of "PG Parental Guidance Recommended".

IanSav has agreed to the use of the icons he created for the OverlayHD skin in the builtin skins.

[prl]

Fixed in skins