Improved theme

[netmackan]

Is your feature request related to a problem? The light gray and yellow text colors does not go well with light background as seen in #118. Additionally, some users prefers a light theme.

Describe the solution you'd like As suggested by @realrufans in #118:

• Let the text color be one that fits both light & holo background. Especially consider the light gray and yellow colors that exists today
• Consider if it would make sense to have an option for changing theme

TBD: Is it common to have theme change in the app? Any examples of existing apps where this is like so TBD: What would be a text color that works with both light & holo?

Describe alternatives you've considered Alternative could be to keep the colors as is which works as long as the dark theme stays. An alternative to having a theme changing option in the app could be if such option already exists in the system (?).

Additional context See #118