Added fixed and delimited text field interface/implementations, moved read operations out of context and into fields.
Fixed reversed comparison in EnsureNotAtEndOfLine
Added unit tests for fixed-width fields and delimited fields with no quoting.
Added unit tests for delimited field with quoting and fixed buggy delimited field implementation.
Fixed accidental assignment instead of concatenation in DelimitedField ctor. Updated to remove escape characters from returned value.
Added unit test for line position when using quoted delimited.
Added unit tests for delimited quoting+escaping.