Rename `Latest version` column and change `Upgrade` icon.

for evaluating in debugger, etc

curl http://json.schemastore.org/package for some reason returns CRLF while corresponding github repo contains LF...

use the same relative path API in both places
normalize slashes for comparison if the user edited manually

some web servers misuse HTTP 301 and use it for internal redirects
using LOG.error leads to showing exception dialog for each URL served by such a server
let's log it as a warning instead

* This is necessary to support relative file references in SVG images

just rename "Add" to "New" to reflect both cases by one item

https://github.com/JetBrains/jediterm/pull/163

Third-party Plugins Privacy Note is shown on attempt to install third party plugin
until user accepts the note