Merge pull request #3363 from ussuri/csp-fixer-improvements

Enable CSP fixer for any folder with HTMLs, not only package directories
Add cache/ to .gitignore (for Pub)
Merge pull request #3364 from ussuri/small-fixes-3

Add cache/ to .gitignore (for Pub)
Merge remote-tracking branch 'upstream/master' into small-fixes-3
Standardize on "Delete..." for delete/remove action on various resource types
Fix a UI message
Merge pull request #3368 from ussuri/small-fixes-3

Fix some UI strings + add Pub-generated cache/ to .gitignore.
Fit most of spark.dart into 80-char width
Merge pull request #3369 from ussuri/small-fixes-3

Fit most of spark.dart into 80-char width
Restrict "Properties" context menu item only to a single selected resource
Revert "Restrict "Properties" context menu item only to a single selected resource"

This reverts commit e02824cb53249b47ac33e606fe8200891fd60b0f.
Restrict "Properties" context menu item only to a single selected resource
Reuse exising function in the prev. commit
Merge pull request #3371 from ussuri/small-fixes-3

Don't show "Properties" context menu item when multiple resources are selected