Add additional_columns to to_pandas

• Fix in readme (@rjtavares)
• Add additional_columns to to_pandas (@rjtavares)

Opta serializer

• Add Opta event serializer
• Fix for event pattern matching for nested captures
• Fix for event pattern matching when multiple paths can match
• Improved ball_recovery example

Code formatting, contributing guide and python 3.6 support

Add code formatting and contributing guide (@dmallory42)
Add support for python 3.6

v0.5.2

Fix Transformer when ball position is not set (@benoitblanc)
Fix for working with periods in EPTS Serializer (@bdagnino)

Extend kloppy-query

• Add stats in json/text format to kloppy-query
• Add show-events to kloppy-query to print all events in the matches
• Change kloppy-query to make it possible to run without an output file

Pattern matching

In this release we introduce pattern matching. Use the power of regular expressions to find situations within event data.

• Add pattern matching based on regular expressions
• Add kloppy-query: command line tool to search for patterns

StatsBomb fix

• Fix for StatsBomb Serializer when location contains z coordinate

StatsBomb events loader

• Add StatsBomb event data loader
• Some fixes in readme
• Refactor some code to get cleaner code
• Pass a logger to performance_logging instead of print to stdout
• Minor fixes in datasets loader caching