idle / resume improvements

[totaam]

• the interface is a bit messy
• we lock the batch delay but leave the quality and speed settings on auto (see Scrolling in Quod Libet causes the server to lock up and stop sending paints #1440#comment:5) - those could be locked too, temporarily bumping the quality to 100% and speed very low (but maybe not 0%)

[totaam]

Time to look at this. improvements already made in #540.

[totaam]

Meh, since the windows aren't visible, using lower quality is not such a huge problem. Adding new packets would require new flags in the client and 2 ways of doings things, making things even harder to read.
The control_refresh is ugly, but it does the job, for now.

[totaam]

Let's deal with this as part of #1942.