Fixed: read up to 4096 chars per line from a strm/m3u file (and use the ...

...full buffer)

Somebody had some issues running my add-on from a strm file but had no issues playing it from a favourite. Turned out that the URL was cut of. I did some debugging and noticed that XBMC only reads 1024 chars per line of a m3u/strm file, even though it's buffer is 4096 chars. 

I changed it to read the full buffer size and it does fix the problem (up to 4096 chars in an url).