experimental solar radiation measurement for cloud cover cause vs is …

…not accurate enough

Use ConfigLib instead of managing config manually

fix potential exception stopping refresh loop

Add error popup

Add support for VisualCrossing

Merge pull request #4 from SynesthesiaDev/feature/memory-optimization

Feature/memory optimization

update schema and readme

Remove lock screen feature

Fix updater

Merge pull request #3 from SynesthesiaDev/feature/implement-missing-c…

…onfig-stuff

Implement missing config stuff