v0.6.0

This version introduces directives to the (still experimental) schema language and introduces a @deprecated directive for marking deprecated fields. It also improves validation error messages, thanks to @yuzhi and @robzhu.

New:

• Schema Language Directives (#376, #382)
• New @deprecated directive (#384)
• Directive constructor and built-ins are now exported from the main module (#381)
• Introspection types are now exported from the main module (71b6a4a)
• Validation: improving overlapping fields quality, may detect new issues (#386)
• Improve validation error message when field names conflict (#363)
• Include possible names when validation fails (#355)
• Error logging for new interface type semantics (#350)

Fixes:

• Deepen introspection query from 3 levels to 7 (#364)
• Printer now correct prints empty block lists (ea5b241)
• Ensure buildASTSchema does not exclude @skip and @include (#380)