adapted changelog

Author: Stephan Sahm

Changelog.md

@@ -6,6 +6,23 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [1.0.0] - 2020-07-19
+### Added
+- extensive `promote_rule` and `promote_typejoin` implementations have been added for Identity,
+  Const, Option, Either, OptionEither.
+- `@either` macro with which you can construct `Either` using ? operator or if-else.
+
+### Changed
+- Option and Either are now represented as `Union` of Identity, Nothing and Const respectively
+- flatten in general is now unified to use `convert` for interoperability between similar
+  container types
+- flatten of ContextManager is again reverted back to not use `FlattenMe` anymore. Instead the
+  inner result value is explicitly converted to `ContextManager`, following the general principal
+  now.
+
+### Fixed
+- foreach for Identity is fixed
+
 ## [0.3.0] - 2020-03-23
 ### Changed
 - flatten on ContextManager is now realised at runtime (the reason was that inaccurate typeinference could not be resolved for ContextManager before). Concretely, if you call `Iterators.flatten(...)` on the ContextManager, a tag `FlattenMe` will be mapped onto the ContextManager. When the ContextManager is run, then a FlattenMe result will be further flattened out. Note that this wrapper is also applied to non-contextmanager types for advanced later flattening of complex nested flatten structures.