This allows PyTensor to infer more broadcastable patterns, by placing the casting inside the MakeVector Op

Co-authored-by: Maxim Kochurov <max.kochurov@pymc-devs.org>

* Redirect installation issues to Discourse

* Remove required reference to documentation on template issue

* Remove required reference to discussion on feature request template

* Fix automatic label on feature request template

* Replace plain issue template with free form developer template

* Fix line endings of empty files

* Use `not in` for membership test

* Remove unused imports

* Fix implicit string concatenation

* Remove python 2 coding statement

* Change python2's Text into str

* Remove useless linebreaks

* Remove useless parentheses

* Use new-style dictionary and set constructors

* There is no more IOError (alias to OSError now)

* Use .format instead of % string interpolation

* Use super() without redundant arguments

* Remove redundant read flag from open

* Avoid building lists unnecessarily

* Use f-strings with python 3.6

* Black reformat
Co-authored-by: Michael Osthege <michael.osthege@outlook.com>

Co-authored-by: Maxim Kochurov <maxim.v.kochurov@gmail.com>

- Lazily create and cache `FunctionGraph`s, the `Composite.perform`
  implementation, C code, and name values
- Use `fgraph_to_python` for `Composite.perform`
- Use the `HasInnerGraph` interface