Notify users about new arb-release

[westram]

At startup of arb fork a version checker, which works through the following procedure:

• load local database (e.g. properties) containing
  • newest revision numbers announced to current arb
  • announce-properties:
    • privacy (do not contact arb website)
    • what to announce (new release only; release+RC; changes in stable development version=trunk)
    • minimum distance between 2 announcements in days (default=7)
    • timestamps:
      • last time any announcement was displayed
      • earliest time for redisplay (see GUI/close buttons below)
• if not opted-out:
  • retrieve information from arb-home.de:
    • current release/release candidate version (revision numbers)
    • newest development revision with updated changelog
    • see #679 for what information shall be transferred to arb-home.de (via URL)
  • if something should be announced, startup GUI

GUI:

• textbox to display announcement
• preferences (how to get announced)
• close buttons:
  1. "I'm busy, show me again tomorrow"
  2. "I'm really busy, show me again in two weeks"
  3. "Got it, do not show this announcement again"

When a close button is pressed

• store retrieved revision numbers as 'announced' (button 3 only)
• update timestamps
• save properties
• terminate

First startup:

• announce the announce-feature
• describe what private data will be revealed to arb-home.de and how it will be used (see #679)
• set current arb-version as last announced version

See also #680.

[westram]

Milestone renamed