Override the default background color on about:epiphany

Use the original background color on about:epiphany
to fill all the page background.

https://bugzilla.gnome.org/show_bug.cgi?id=725245
Change the text title in help for h.g.o
Updated Czech translation
Updated Czech translation
embed: actually hide the progress bar for about: uris

If the progressbar was already visible, we'd never really hide it.
Do it now.
embed: Remove ephy_embed_prefs_init/shutdown methods

Create the WebKitWebViewGroup object on demand when the first web view
is created.
Added Russian help translation
Disable actions that open new windows
Remove the open new/in existing window flags and always create the new tab in the given window
Remove unused flag EPHY_NEW_TAB_FULLSCREEN_MODE
Decouple the page load from the tab creation

The flags used to decide whether to load the page and how are confusing,
because they are mutually exclusive, which adds more complexity to
ephy_shell_new_tab. Also, ephy_shell_new_tab doesn't always create a new
tab, depending on the parameters and flags, it might reuse an existing
empty tab. All this is easier to handle from the callers if we make
ephy_shell_new_tab always create a new tab that is returned and callers
can decide what to load in the new tab.
Remove flag EPHY_NEW_TAB_PRESENT_WINDOW

It's simpler to call gtk_window_present by the callers.
embed-utils: Invert the logic of condition in ephy_embed_utils_address_has_web_scheme

So that we don't need to do all the string comparisons always.

https://bugzilla.gnome.org/show_bug.cgi?id=725081
embed-utils: Add ephy_embed_utils_address_is_valid

Helper method used to check if a url is valid to decide whether to load
it or perform a search. It's mostly the same expression used by
EphyWebView, but moved to a helper function. The regular expressions used
in that expression are also moved to embed-utils and they are only
compiled once instead of everytime a web view is created.

https://bugzilla.gnome.org/show_bug.cgi?id=725081
embed-utils: do not try to prepend http:// to normalize a URL if it already has a web scheme

https://bugzilla.gnome.org/show_bug.cgi?id=725081
embed-utils: Move ephy_web_view_normalize_or_autosearch_url to embed-utils

And use it only for actually typed (or pasted) text.

https://bugzilla.gnome.org/show_bug.cgi?id=725081
Revert "embed-utils: Invert the logic of condition in ephy_embed_utils_address_has_web_scheme"

This reverts commit 8f441f2aa17bb2597753a44bb6d20cba24f71308.
snapshot-service: Add a memory cache of snapshots paths saved

And add a method to query that cache.

https://bugzilla.gnome.org/show_bug.cgi?id=725393
snapshot-service: Update snapshots after one week

https://bugzilla.gnome.org/show_bug.cgi?id=725393
snapshot-service: Add methods to get the snapshot path

This is useful for the new overview that doesn't need the actual
snapshot, but the path of the snapshot when it has been saved in the
cache.

https://bugzilla.gnome.org/show_bug.cgi?id=725393