IDEA-102405 Arrangement: Refactor the API in accordance with design problems discovered during non-java arrangement implementations

Corrected arrangement settings UI processing for conditions which have user-defined values (text fields)
URLUtil: fix splitScheme()

* Don't add the separator to the URL part.
* Scheme part: return "" instead of null to simplify work for clients.
Move StringUtil.startsWithIgnoreCase to StringUtilRt
[git] IDEA-103110 Fix http authentication for older Git versions.

Gits before 1.7.9 didn't specify the URL in the username/password
request. They just asked "Password: ".

1. Support this kind of request in GitAskPassApp.
   Pass "" as the URL if it is not specified.

2. Get the URL from the GitHandler, to show the URL in the
   authentication dialog, and to use it as a password safe key:
   * setRemoteProtocol -> setUrl, remember the URL in GitHandler,
     parse the protocol in-place where needed.
   * Pass the URL to the GitHttpAuthService, which in turn passes it to
     the GitHttpGuiAuthenticator.
   * GitHttpGuiAuthenticator: if the url is not given in the XML RPC
     request, use the URL passed to the Git command.
     But take only the host to use it in the password safe,
     not to have separate keys for each URL on the same host.
[git tests] add the missing test step
New helper methods added to SyntaxHighlighterBase.