Fixed bug in output from parser test.

Replaced import * with explicit name imports.

Converted os.path to pathlib and all #! lines to python3 (ref #32).

Converted all print statements to functions for Python 3 (ref #32).

• Fixed parsing bug that produced incorrectly structured timestamp lists when using a duration file (introduced by restructuring of grammar).

• Added config5.txt to test files. ...

• Initial work on improving error reporting (catching parser exceptions).
• Some refactoring and rationalisation of the grammar.

• Reconfigured grammar to handle missing components in timestamps (closes #16). ...

• Refactored defaults setting so that it can be easily generalised to new cases.

• Removed unused literals hyphen and comment_char.

• Normalised terminology around “streams” (closes #21).

• Default all missing fields to None instead of 0 or "" so we can check whether there actually is a value assigned if necessary.

• Finished support for generating frames directly from PDF slides (closes #8). ...

• Specified defaults for audio and video stream numbers.
• Fixed some typos on comments and debug output.
• Added "/" as a valid filename character for config files.
• Added some comments explaining the more obscure class variables in the Segment class.
• Generalised Segment.generate_last_frame() into generate_frame().
• Ensured that generate_temp_file() returns the generated filename.

• Moved segment classes into separate module (closes #7). ...

• Moved global configuration into separate module.
• Made format of debug logging more consistent.
• Added a few more info logging messages.
• Renamed configuration parser module.