v0.4.0

TensorKit v0.4.0

Diff since v0.3.0

Merged pull requests:

• Add Dict and Pair constructors for Cartesian and Complex spaces (#27) (@mhauru)
• fix small typos (#28) (@ho-oto)
• fix typos (#29) (@ho-oto)
• Add real and imag. (#30) (@mhauru)
• fix some typos (#31) (@ho-oto)
• remove typo and broken link (#32) (@ho-oto)