Add option for coloring pending tasks and setting the default row color.

At the moment it seems to be impossible to colorize neither pending tasks nor set the default color of the output.

It would be great to be able to have that feature so that one would be able to set different color for the task table so it would pop out contrast wise from the rest of the text in the terminal.

I propose following additional color settings:

```
color.default=<...> on <...>
color.pending=<...> on <...>
```