Using widgetId as the key when rendering elements (streamlit#1102)

* develop: (29 commits)
  Release 0.56.0 (streamlit#1101)
  Fix bug where icon assets were missing from "make install" (streamlit#1100)
  Clean signatures of wrapped DeltaGenerator methods (streamlit#1099)
  Using widgetId as the key when rendering elements (streamlit#1102)
  Pass --skip-lock to pipenv under pipenv-install Makefile target. (streamlit#1093)
  Allow wider range of int-like types in NumberInput (streamlit#1087)
  Fix missing caching URL (streamlit#1094)
  Version 0.55.1 (just pointing to new docs) (streamlit#1089)
  Retire python-3.7.4 CircleCI project. (streamlit#1086)
  Handle different Caching error messages (streamlit#1068)
  Fix an incomplete copy for a dict that's then modified. (streamlit#1078)
  Fix indentation error in fad994c. (streamlit#1084)
  Widgets unit tests (streamlit#1077)
  [mypy] First phase of work on testing Python type annotations. (streamlit#1079)
  Add CircleCI jobs to run the oldest and newest Python versions we support. (streamlit#1053)
  Improve docs (streamlit#1075)
  Adding CORS to troubleshooting guide. (streamlit#1001)
  Fix for the CORS check (streamlit#965)
  Advanced caching updates feb (streamlit#1040)
  Fixing add_rows index calculation (streamlit#1054)
  ...

* develop: (30 commits)
  [Screencast] Fixing countdown bug (streamlit#1082)
  Release 0.56.0 (streamlit#1101)
  Fix bug where icon assets were missing from "make install" (streamlit#1100)
  Clean signatures of wrapped DeltaGenerator methods (streamlit#1099)
  Using widgetId as the key when rendering elements (streamlit#1102)
  Pass --skip-lock to pipenv under pipenv-install Makefile target. (streamlit#1093)
  Allow wider range of int-like types in NumberInput (streamlit#1087)
  Fix missing caching URL (streamlit#1094)
  Version 0.55.1 (just pointing to new docs) (streamlit#1089)
  Retire python-3.7.4 CircleCI project. (streamlit#1086)
  Handle different Caching error messages (streamlit#1068)
  Fix an incomplete copy for a dict that's then modified. (streamlit#1078)
  Fix indentation error in fad994c. (streamlit#1084)
  Widgets unit tests (streamlit#1077)
  [mypy] First phase of work on testing Python type annotations. (streamlit#1079)
  Add CircleCI jobs to run the oldest and newest Python versions we support. (streamlit#1053)
  Improve docs (streamlit#1075)
  Adding CORS to troubleshooting guide. (streamlit#1001)
  Fix for the CORS check (streamlit#965)
  Advanced caching updates feb (streamlit#1040)
  ...

* develop: (53 commits)
  Update plotly.js to 1.52 (streamlit#1119)
  Add tooltip in Altair/Vega-lite docstring code (streamlit#1092)
  Ability to bind to a server address with server.address config option (streamlit#1107)
  [mypy] Enable check_untyped_defs throughout the codebase. (streamlit#1110)
  st.map: set "radiusMinPixels" to 3 (streamlit#1113)
  st.plotly_chart docs incorrectly refer to Altair (streamlit#1118)
  Fix BytesIO and numpy array data sources for audio/video (streamlit#1116)
  Show warning to user and use skipkeys=True if json.dumps causes TypeError (streamlit#1112)
  Server: store SessionInfo by id (streamlit#1056)
  [Screencast] Fixing countdown bug (streamlit#1082)
  Release 0.56.0 (streamlit#1101)
  Fix bug where icon assets were missing from "make install" (streamlit#1100)
  Clean signatures of wrapped DeltaGenerator methods (streamlit#1099)
  Using widgetId as the key when rendering elements (streamlit#1102)
  Pass --skip-lock to pipenv under pipenv-install Makefile target. (streamlit#1093)
  Allow wider range of int-like types in NumberInput (streamlit#1087)
  Fix missing caching URL (streamlit#1094)
  Version 0.55.1 (just pointing to new docs) (streamlit#1089)
  Retire python-3.7.4 CircleCI project. (streamlit#1086)
  Handle different Caching error messages (streamlit#1068)
  ...