Provide parameters in URL

[jgieseler]

Introduce the possibility to provide parameters that are set in the left bar directly in the URL. This would enable the user to:

• save a specific layout as a bookmark (handy so that one doesn't have to set all the parameters again and again)
• share a specific layout with others

URL could e.g. look like this: https://solar-mach.github.io/?date=20200417&time=0130&bodies=Earth,BepiColombo,PSP&vsw=400,300,500

[jgieseler]

In general, the functionality is working now. A URL like https://share.streamlit.io/jgieseler/solar-mach?date=20210407&time=1630&plot_nr=1&bodies=STEREO+A&bodies=Earth&bodies=BepiColombo&bodies=Parker+Solar+Probe&bodies=Solar+Orbiter&speeds=400&speeds=400&speeds=400&speeds=400&speeds=400& is clunky but doing its job.

Still an open issue is that the URL parameters so far only work with the full share.streamlit.io/jgieseler/solar-mach URL, but not with the "official" solar-mach.github.io address that is redirecting through an iframe element in the index.html.

[jgieseler]

Maybe it's worth trying to replace the current system using st.experimental_get_query_params() and st.session_state with the one provided by https://pypi.org/project/streamlit-ext/. Because with that in theory the URL should be updated with the current set of settings "on the fly", and in addition adding new parameters would be much easier. (st.experimental_get_query_params() is an experimental feature anyhow.)