Update gst123.cc

[zhashuyu]

feat: decode filename from uri to normal string
(文件名由URL格式改为终端识别的字符)
from: Playing file:///home/boomer/A_DRIVER/Music-need-sync/%E9%9F%A9%E9%9B%AA/%E9%9F%A9%E9%9B%AA-%E6%83%B3%E8%B5%B7.mp3
to: Playing file:///home/boomer/A_DRIVER/Music-need-sync/韩雪/韩雪-想起.mp3

[swesterfeld]

I have reworked your code to match gst123 coding style and committed it as 11c52fe - please test and let me know if everything works as expected for you.

I didn't understand why I should specialcase "+" occuring in the URI, so I currently don't do that, as a filename on disk could contain a + sign, and I should be able to copypaste the filename output from gst123 and be able to play the file.

[swesterfeld]

Btw, the common case is probably that we are playing back some file that is stored locally (file:///...), for this case it probably makes sense to just display the filename without any prefix, I've done this now like this: 4846586