Pyvhdlmodel

**Created on: 21.06.2021 - 17:49:04**

New Features
* `Alias`
* `IndexedObjectOrFunctionCallSymbol`
* `SubExpression` / `QualifiedExpression` / `Parenthesis` as `typing.Protocol`
* `Component`
* `Physical...Literal`

Changes
* Swapped `NegationExpression` and `InverseExpression` to match unary `not` and `-` operators.

Bug Fixes
* tbd

**Created on: 19.06.2021 - 10:10:11**

New Features
* Added `Agregate` and classes derived from `AggregateElement`
* Added `ParenthesisExpression`
* Added `EnumerationLiteralSymbol`
* Added `__str__` to expressions, literals, aggregates and ranges.

Changes
* Added property `Object` to `SimpleObjectSymbol`

Bug Fixes
* tbd

**Created on: 17.06.2021 - 11:29:49**

New Features
* Added symbols (unresolved symbolic names to existing model entities).
* Add type aliases including Expression.

Changes
* Renamings:
* LibraryReference to LibraryStatement.
* PackageReference to UseStatement.
* ContextReference to ContextStatement.
* Expression to BaseExpression.

Bug Fixes
* Missing calls to parent method.

**Created on: 13.06.2021 - 21:37:55**

New Features
* Added missing object representations for language features.
* Finalized literals, expressions and types.
* Added properties to empty placeholder classes
* Enhanced class documentation and cross references.
* New documentation chapter for literals and expressions.
* Added inheritance diagrams as overviews to documentation sections.
* Added condensed code snippets outlining the main interface of a model's object.
* New Single-File GitHub Action workflow (pipeline) including tests, documentation, packaging and publishing.
* Added Dependabot configuration file.

Changes
* Made generic, port, and parameter items a subclass of the matching object classes.
* Removed 2 dependencies to patched Sphinx extensions (now fixed in Sphinx).

Bug Fixes
* Corrected class hierarchy according to LRM.

Changes
* Renamed `Use` to `PackageReference`.

* Added documentation license (CC-BY 4.0)
* Updated and fixed badges (shields)
* Changed test runner to `pytest`
* Removed editor specific file headers (replaced by editorconfig)
* License screening and dependency check (also documented).
* Uploaded PyCharm project files and settings.