Add support for 0.9.7/8

[kannibalox]

A primary goal was not to effect .6 builds, and when the patches are applied both before and after my changes, the code is the same line-for-line.

Other notes:

• support was dropped for 4/5, I assumed that wouldn't be a big deal
• I was frankly too lazy to deal with backport_0.9.7_add_temp_filter-CH.patch and its baggage when it wasn't being used and shows up merged in 8 anyway, so I just removed it
• it might be possible to reduce the sheer number of files by using more #if statements, but I figured this would reduce the chance of bugs in each version
• I found just eye-balling git a hard way to keep track of the big picture, so here's a CSV summarizing the changes https://gist.github.com/kannibalox/9889ad6c0f22522e5cf7bbb9f94d3381

[kannibalox]

i missed a rather glaring bug in 0.9.8: Ctrl-F crashes rtorrent after input, and F for a temp filter doesn't trigger at all. The former is not too surprising, but the latter is rather mysterious. I'm working on solving the temp filter first, but it seems like the find feature might require actual c++ programming, at which i suck.

[pyroscope]

There is that endless loop when no hit found thing, you thought of that?

I'm trying to merge this in the next few days. We can always add fixes afterwards. And you can compare what's here with what is in mainline.

[kannibalox]

To be honest, after this first bug i strongly considered remapping Ctrl-F to F entirely,

And you can compare what's here with what is in mainline.

I did that in git, but i must be missing something obvious because i still don't see what's breaking F

[Sinderella]

I wonder what's the state of this PR? I think I came across some weird bugs that don't appear in 0.9.8, so I'd like to give this a shot.

[kannibalox]

I've been using this build since I first pushed it with no issues, however the UI still has problems per as above and i have not done comprehensive testing.