Created README.md

Information on installation and documentation
BUGFIX: fix call to tier_type()
BUGFIX: fix remaining calls to tier_type()
BUGFIX: unicode type conversion
Bumped version number to 1.0.1
Added an option to include empty intervals for specific tiers.
Update a docstring.
Updated io3.py
Aliased get_annotations_with_matching_text as get_annotations_with_text.
Changed get_nearest_annotation to return a list (sorted by start times).
Added a CITATION file.
Bumped version to 1.0.2
Added __getitem__ method to Tier.
BUGFIX: moved an import statement from core.py to util.py
Added functions to calculate chronograms.
Further improvements to chronogram calculation.