New underline scheme for cpp type files according to the type of error messages

For cpp-type files, there are two types of error:
1. warning 
2. error
Currently geany colors the line generating any of the above type of message same way. I have made changes so that geany is able to differentiate whether the line caused warning message or error message.
As Dimitar pointed out "that parse_file_line() returns if length(fields) is less than data->min_fields. With the above change, anything with < 4 colons will be rejected." So I changed the function to extract all available tokens and then try to extract the line number and type of error message. I have also put a check to see if the fields array access is within range