status bar improvements

[linuxcaffe]

There is already some information in the utw statusbar, but it could use a couple more things.
Currently, from a tasklist, I see

Unite > default > taskwarrior (201) |                                   < [Unite] -default

now I'm not entirely sure what "default" actually refers to, If it's a default utw tasklist, then maybe that should just be "tasklist". Another thing that should always be displayed is the current context, and a bit more info about the # of tasks and the # of the current filter set would be good. Some of this is inspired by the vim-tw status bar, How about also showing the current ID and sort-order?

(updated)

Unite taskwarrior  > @none > filter terms (52/201) $L |          142 ID  < [Unite] -tasklist

I'm probably misunderstanding how the taskbar works, but the above information would be very helpful.

[blakesweeney]

I'm not sure how much control over the statusbar I have. It is done by unite.vim, but I'm not sure of what hooks exist to control it. I'll need to look into this a bit.

[linuxcaffe]

vim-tw is an excellent model here, using unite and very informative