v0.9.0

AbstractPPL v0.9.0

Diff since v0.8.4

Merged pull requests:

• Conversion of VarName to/from string (#100) (@penelopeysm)
• Build and publish API docs (#101) (@penelopeysm)
• Add compat bounds for JSON (#102) (@penelopeysm)

Closed issues:

• condition method with weights (#39)
• serialisation / deserialisation of VarName (#98)
• Colon doesn't subsume itself (#99)