#590 ass transparency support

[zm1990s]

I don't know why we can't use both normal subtitles and SSA/ASS subtitles.
I like the colour of normal subtitles, seems it has tranparency.
I know .ass files supports transparency, it can use html colors like &H60000000, but, you know, in ASS subtitles settings, you can only use colors like #FAFAE4.

And you might say you can use 'Apply style to ass files too' and set a customize style, I've tested, if I choose this, some ass files will get wired, I'm a Chinese so I ofen use subtitles with two languages, in that case English text will get very big (I don't know what happened)

And and , I don't know why seperate normal subtitles and ass settings? Couldn't be .srt files use normal subtiles settings and ASS/SSA use ASS settings?