Layered-vision

* bumped tf-bodypix to 0.3.6 (150)
* added `mp_selfie_segmentation` (MediaPipe) filter (140)
* web stream output (135)
* fix combine image with dtype int; added `poly_points` support to `fill` filter (122)
* added `fill` source and filter (101)
* implemented fallback error handling (100)
* fixed video input was sometimes returning none image (99)
* added `warp_perspective` filter (98)
* added `multiply` filter (96)
* added `invert` filter (95)
* reloadable config (94)
* fixed slow example config tests (81)
* added mypy checks (80)
* improved combine images (77)
* various library upgrades

added optional enabled flag (76)
added bilateral filter (75)
allow window_title to be specified (73)
added screen capture support via mss (72)
dynamically load sources and sinks (71)

* added youtube live stream support (67)
* allow overriding non-str values (69)
* fixed override map not applied to nested layers (including branches) (66)
* various dependency updates

* added docker image (39)
* added option to override values via cli (38)
* added png transparency support (37)
* disabled webcam buffering (36)
* configured package extras (31)
* test on windows and mac (30)
* refactored filters (29)
* added example tests (28)

* added pixelate face example (23)

* initial release