* develop: (31 commits)
  fixed misspell (streamlit#712)
  Add ConfigOption attribute "scriptable" w/ only some options scriptable=True (streamlit#702)
  Fixing Tornado on Windows + Python 3.8 (streamlit#682)
  Moving reportId and metadata from Element to ReportElement (streamlit#529)
  Fall back on webbrowser if xdg-open is not installed on Linux (streamlit#701)
  Dockerfile: ensure we install the NODE_VERSION we reference elsewhere (streamlit#639)
  Datepicker pop-up aligned on left (streamlit#676)
  Fixing number input spin buttons for Firefox (streamlit#683)
  Fixing makeElementWithInfoText (streamlit#692)
  Fixing CTRL+ENTER on Windows (streamlit#699)
  Add option to use PollingFileWatcher, even if watchdog is available (streamlit#626)
  Break util.py into several util files (streamlit#703)
  Do not automatically create credential file when in headless mode (streamlit#467) (streamlit#603)
  make __future__ import be the first line (streamlit#687)
  Split text protos (streamlit#506)
  pandas.isna was introduced in version 0.21.0 (streamlit#679)
  Prefix get_report_ctx with underscore in __init__ and import it correctly in (streamlit#669)
  Fix single word in changelog (streamlit#672)
  Move some functions from util.py into type_util.py (streamlit#670)
  Release 0.50.2 (streamlit#666)
  ...

* develop: (38 commits)
  Add viz.js to the repo (streamlit#635)
  fixed misspell (streamlit#712)
  Add ConfigOption attribute "scriptable" w/ only some options scriptable=True (streamlit#702)
  Fixing Tornado on Windows + Python 3.8 (streamlit#682)
  Moving reportId and metadata from Element to ReportElement (streamlit#529)
  Fall back on webbrowser if xdg-open is not installed on Linux (streamlit#701)
  Dockerfile: ensure we install the NODE_VERSION we reference elsewhere (streamlit#639)
  Datepicker pop-up aligned on left (streamlit#676)
  Fixing number input spin buttons for Firefox (streamlit#683)
  Fixing makeElementWithInfoText (streamlit#692)
  Fixing CTRL+ENTER on Windows (streamlit#699)
  Add option to use PollingFileWatcher, even if watchdog is available (streamlit#626)
  Break util.py into several util files (streamlit#703)
  Do not automatically create credential file when in headless mode (streamlit#467) (streamlit#603)
  make __future__ import be the first line (streamlit#687)
  Split text protos (streamlit#506)
  pandas.isna was introduced in version 0.21.0 (streamlit#679)
  Prefix get_report_ctx with underscore in __init__ and import it correctly in (streamlit#669)
  Fix single word in changelog (streamlit#672)
  Move some functions from util.py into type_util.py (streamlit#670)
  ...