/*
* call-seq:
* text ( x, y, text, color=0, font=<lru or "cetus">, size=<lru or 20> ) -> nil
*
* Draws a text with specified parameters. If font and fontsize given,
* it is saved for future call of Osd#text and Osd#text_size.
*/
static VALUE osd_text(int argc, VALUE *argv, VALUE self) {