v7.0.0

Breaking changes:

• Update project and deps to PureScript v0.15.0 (#39 by @nwolverson, @JordanMartinez, @sigma-andex)
• Update write/writeString/end callbacks to include Maybe Error arg (#40 and #43 by @JordanMartinez)

Bugfixes:

• Exported destroyWithError (#43 by @JordanMartinez)

Other improvements:

• Fix Gzip example (#17, #36 by @matthewleon and @JordanMartinez)