Started development on 1.8~dev
Fixed a bug where from_filename is not passing extra

The from_filename contructor doesn't pass extra arguments to the
original contructor, this disable feature such as the schema validation.
Fixed examples in readme and docs

Thanks to Stefan Tschiggerl for the report.
Fixed bad API usage in containers' argument validation

Thanks to Stefan Tschiggerl for the report.
Handle the uniqueness validation of empty args

Thanks to Stefan Tschiggerl for the report.
Corrected basic examples
Added single subsection access method

This function is similar to subsections method. However, it does not return a
list but a single ConfigSection. It is only allowed to be called if there is
exactly one section of this type, so schema has meta 'repeat': (1,1)
Fixed optional section without occurrence not working (ref #7)
Fixed a bug when subsection method is used twice with the same name
Fixed traceback when a section is not in schema (ref #6)
Added input_name for lexer

This solves a traceback error if t_error function is called since it uses
self._input_name for creating a Position object.
Passed input_name to parser

In Position object, a filename is stored to output if an exception
occurs (ParsingError, ValidationError). This value was never set since Dotconf
object never passed an input_name to the parser.
Released version 1.8