added some white icons,
changed hardcoded icons to theme attributes,
changed icon_edit_dark to icon_edit_body to reflect icons position,
grey message bubbles in dark theme,
misc
purged ic_action_chat as it wasn't used
preference use_white_background changed to use_green_background, default true
grey chat bubbles darker, text white
replaced all grey600 with black icons and 0.54 alpha attribute
highlightColor in dark grey chat bubble now darker than background
Martin/Geno
Steffen Keiper