Taskbook output color

**Is your feature request related to a problem? Please describe.**
Taskbook's output becomes unreadable when the terminal background color is identical or similar
to the text color.

**Describe the solution you'd like**
Being able to change the text color with the taskbook config file would solve the problem and offer some customization.

I use the terminal emulator "Terminator".

**Screenshots**

Start by locating Taskbook's configuration handling and the code that formats terminal output. Add a configurable text-color option and verify that the output remains readable when the terminal background is similar to the default text color.

Written by the indexing model from the issue text.