Merge pull request #744 from srazi/master

Better RTL support for LocationCompleter and add direction property to dirlist.html
Sending information about versions in reportbug page.

Improved OS detection on Windows. It will also show version
of Windows (except Win 8)
Improved parsing of Content-Disposition header.

It now tries to detect whether UTF-8 encoding is used.
Closes #745
Don't show AdBlock icon in webview context menu on editable content.
[sourceviewer] Option to load edited source code in page.

Also fixed showing AdBlock css rules when reloading source.
[spellcheck] Adding Speller object into MainApplication.
[spellcheck] Added context menu options to replace misspelled words.

And also to add word into user dictionary.
[spellcheck] Added dialog with spell check settings.
[code] Using QVariant::fromValue instead of obsolted qVariantFromValue.
[spellcheck] Fixed replacing words in multiple lines text.
[spellcheck] Enable SpellCheck on Windows by default.
Fixed scrolling to anchor(#) links in background tabs.

Setting correct QWebPage::viewportSize() on creation.
Closes #663
[jsoptions] Added "Disable or change context menu" option

User can now set whether sites are allowed to change or
completely disable context menu.
Fixed crash with "Allow js to disable context menu" option.

See f6de3bd5a01b6f9468b0dcf32744a879e811c255
Properly returning page to its original state after rendering preview.

See #663
[adblock] Added support for $image rules.

It tests whether the url ends with .jpg/.jpeg/.gif/.png
[adblock] Added RU Adlist into known subscriptions.
Disabled opacity effect in animated tab previews by default.

It can still be enabled with ENABLE_OPACITY_EFFECT build variable.
This is final fix for #663
[spellcheck] Fixed adding some words into user dictionary.
[code] Added checks before using QWebPage::view().