Update to 2.20

* Merge SunOS patches from www/firefox.

Changelog:
SeaMonkey-specific changes

    The Content Security Policy (CSP) 1.0 parser has been enabled.
    The Mixed Content Blocker has been enabled, blocking insecure active content loads on HTTPS pages.
    New mail alert information can be customized now (Preferences/Mail & Newsgroups/Notifications).
    A confirmation prompt has been introduced to protect against accidental permanent data loss when force-deleting messages using Shift+Del.
    MailNews Save As Template supports multiple selections now.
    The size on disk is now shown for newsgroup folders.
    See the changes page for a more complete overview.

Mozilla platform changes

    Added support for scrollbar style in Mac OS X 10.7 and newer.
    Enabled mixed content blocking to protects users from man-in-the-middle attacks and eavesdroppers on HTTPS pages (learn more).
    Improved about:memory's functional UI.
    Enabled DXVA2 on Windows Vista+ to accelerate H.264 video decoding.
    Simplified interface for notifications of plugin installation.
    Enabled users to switch the search provider across the entire browser.
    CSP policies using the standard syntax and semantics will now be enforced.
    Implemented the HTML5 <input type="range"> form control.
    Added unprefixed requestAnimationFrame.
    Dropped blink effect from CSS rule text-decoration:blink and completely removed <blink> element.
    Fixed several stability issues.

Fixed in SeaMonkey 2.20
MFSA 2013-75 Local Java applets may read contents of local file system
MFSA 2013-74 Firefox full and stub installer DLL hijacking
MFSA 2013-73 Same-origin bypass with web workers and XMLHttpRequest
MFSA 2013-72 Wrong principal used for validating URI for some Javascript components
MFSA 2013-71 Further Privilege escalation through Mozilla Updater
MFSA 2013-70 Bypass of XrayWrappers using XBL Scopes
MFSA 2013-69 CRMF requests allow for code execution and XSS attacks
MFSA 2013-68 Document URI misrepresentation and masquerading
MFSA 2013-67 Crash during WAV audio file decoding
MFSA 2013-66 Buffer overflow in Mozilla Maintenance Service and Mozilla Updater
MFSA 2013-65 Buffer underflow when generating CRMF requests
MFSA 2013-64 Use after free mutating DOM during SetBody
MFSA 2013-63 Miscellaneous memory safety hazards (rv:23.0 / rv:17.0.8)
Updated www/seamonkey to 2.20