Security update for MozillaThunderbird (important)

This update for MozillaThunderbird fixes the following issues:

Thunderbird 63 ESR was updated to version 60.3.0 to fix the following
issues (bsc#1112852):

Security issues fixed (MFSA 2018-28):

• CVE-2018-12389: Fixed memory safety bugs.
• CVE-2018-12390: Fixed memory safety bugs.
• CVE-2018-12391: Fixed HTTP Live Stream audio data is accessible
  cross-origin.
• CVE-2018-12392: Fixed crash with nested event loops.
• CVE-2018-12393: Fixed integer overflow during Unicode conversion while
  loading JavaScript.

Non-security issues fixed:

• various theme fixes
• Shift+PageUp/PageDown in Write window
• Gloda attachment filtering
• Mailing list address auto-complete enter/return handling
• Thunderbird hung if HTML signature references non-existent image
• Filters not working for headers that appear more than once