Go to tasks; kinda 'agenda'

This patch allows to view list of tasks with all and specific tag in quick panel.
It's kinda unfinished, but I'm not a pro :)
How to use:
1) press ctrl+shift+r
![1](https://f.cloud.github.com/assets/1975298/139738/ec70fea4-7203-11e2-9b49-aa72c062eab9.png)
2) specify
![2](https://f.cloud.github.com/assets/1975298/139741/f7c0fce6-7203-11e2-8be2-79d773dfd9fb.png)
3) choose task with arrow keys and press enter
![3](https://f.cloud.github.com/assets/1975298/139742/14c7dfc6-7204-11e2-85ca-cd69859f01b3.png)
It will scroll if necessary.