Symbolica 0.17.0

Symbolica 0.17.0 has been released!

Notable changes

• Complex number coefficients (2x+ix = (2+i)x), complex number parsing and conjugate method
• Multivariate apart
• No more unwrapping for parse and symbol
• Introduction of held expressions and Expression.hold (see here)
• Custom printing for symbols
• States in transformer chains (stats can now be printed as json)
• Shorthand T() for transformer construction

Upgrade notice*

• parse! and symbol! will unwrap, removing boilerplate, use try_parse! and try_symbol for fallible parsing
• e.transform().expand() now reads e.hold(T().expand())