Improve CSS colors
This is an attempt to improve the Gajim's colors. Colors in Gajim are used to highlight various things. I tried to get better contrast on one hand, and to unify colors from light and dark themes on the other hand.
What I changed:
- ChatControl: status label contrast was too low > removed
dim-label
class - HistoryWindow: search highlight color was coupled to directed group chat messages > own search highlight class
- Status messages in chat: green suggests go/online > changed to neutral blue
- Highlight messages/directed group chat messages: unified tab label color and text color of directed messages
- Roster connected/disconnected: changed to green/red
- Chatstate composing: changed from dark blue to turquoise to lower the color distance between composing and paused
- Group chat tab new message: better contrast in dark theme
- Various contrast improvements