ide colors: Change names and usage of colors variable in gconfig

Adds: error_color_fg: color of the font of an error in source (red) error_color_bg: color of the background of an error in source (white) error_line_color: color of the line of an error in source (yellow) error_color_msg_zone_fg: color of font error in the message zone (red) error_color_msg_zone_bg: color of background error in message zone (yellow)

also fix #392 (closed)