Bug in LineReader

[ppwwyyxx]

The LineReader has the following logic at https://github.com/ben-strasser/fast-cpp-csv-parser/blob/master/csv.h#L466 to check whether the file ends with "\n":

                        while(buffer[line_end] != '\n' && line_end != data_end){
                                ++line_end;
                        }

                ......

                        if(buffer[line_end] == '\n'){
                                buffer[line_end] = '\0';
                        }else{
                                // some files are missing the newline at the end of the
                                // last line
                                ++data_end;
                                buffer[line_end] = '\0';
                        }

However this is wrong in the following conditions:

1. there is a missing "\n" at the end of the last line in the file
2. buffer[line_end] (which contains uninitialized random memory data) happens to be "\n"

In the above case, data_end is not correctly incremented, and cause an assertion error later.

[ben-strasser]

I believe this is fixed with the latest commit. If not, please reopen.