Merge pull request #163 from QuendiMax/master

Add belarusian localization
History Pane rewrite.

The new History Pane features proper mouse and keyboard navigation,
multiple selection and ability to remove the selected entries,
plus a dynamic context menu. Additionaly, the History's size is now
configurable in Preferences.

Use Ctrl+H to show/hide the History Pane.

History Pane's titlebar can be styled via #historyPaneTitleBar, e.g.:

/* Colored header for the History Pane */
  background: lightsteelblue;
  margin: 2px;
}

Closes #162: Make History sidebar independent from the Search Pane
Closes #159: "Send to main window" button from Pop-Up window does nothing when History is shown
Closes #158: Preserve History mode after restart
Closes #157: History with new UI: New words are not added when History is shown
Closes #156: History with new UI: Extra Groups widget in History is shown
Closes #155: History with new UI: Arrow keys navigation in History doesn't work
Closes #154: History with new UI: DEL key does not delete the current history entry
Implemented History copying to the clipboard
Make the default history item length to be the same as the limit for the headwords.

So, it is 256 now.

And configurable via the same parameter in the config file: maxHeadwordSize.
Preserve the current index in History list when a single entry is deleted.
Lupdate all translations, update Russian translation
Compare History items case insensitively.
Remove rather useless context menu to add title to history.

In most cases, since we are on this page, we have already
just added its title to the history.
Revert "Remove rather useless context menu to add title to history."

This reverts commit c03b3461140df2b24e01e9203325b723cbe0fd6f.

The menu item is not completely useless, it useful when the automatic history
gathering is disabled and this menu could be used to add items to the history
manually.
Better way of dealing with adding title to history.

We only show that menu item to add the title to history if the
history is set to only collect the entries manually.
Update Argentinian Spanish translation
Fixed #167: Not everything gets logged in History
Handle big entries in bgl
Fixed #164: Add an option to copy the entire article (Ctrl+A)
Select an enire text of the current article (Ctrl+Shift+A).

Plus a context menu for that as well.
Lupdate all translations, update Russian translation
Make the popup window more compact by reducing margins and spacing to 3px.

There is no point in having huge margins (9px) at every side of the
scan popup window. Especially since the popup window is supposed
to be small and compact.
Ignore GoldenDict.app directory
Do not store the welcome page in the user history.
Add belarusian transliteration