Support extension types, fixed size list and fixed size binary

What's Changed

• Update python dataset generation to use boolean and dictionary encoding. by @eddyxu in #124
• Basic python extension types for image, point2d, and box2d by @changhiskhan in #102
• Fix offset calculation in VarBinaryEncoder for slices by @eddyxu in #128
• Support pyarrow write_dataset with partitions by @eddyxu in #125
• Add encoding for FixedSizeBinary and FixedSizeList by @eddyxu in #129
• Support parsing fixed size list in schema by @eddyxu in #130

Full Changelog: v0.0.4...v0.0.5