More info in "Unexpected end of key/value pairs" error

Previously it was hard to know where the error was coming from if you
had a large number of include files. This makes it easier by printing
the string value and the section in which it occurred.
Merge pull request #515 from msabramo/pinpoint_unexpected_end_of_key_value_pairs_error

More info in "Unexpected end of key/value pairs" error