Add InactiveFloaterTransparency and ActiveFloaterTransparency settings

Dear Users,
This removes FloaterUnfocusedBackgroundOpaque, to achieve the same effect,
modify InactiveFloaterTransparency, 1.5 should do the trick.

PS: The settings are in the Vanity tab at the bottom.

Now for developer nonsense:
Also sync a bunch of the UI code with upstream Alchemy for opts and shtuff.
Also let's translate the tooltips on the buttons on the top right of floaters
Translators note that not all new strings have been translated yet as not all are upstream.

indra/llui/llfocusmgr.cpp

@@ -33,10 +33,10 @@
 const F32 FOCUS_FADE_TIME = 0.3f;
 
 LLFocusableElement::LLFocusableElement()
-:	mFocusLostCallback(NULL),
-	mFocusReceivedCallback(NULL),
-	mFocusChangedCallback(NULL),
-	mTopLostCallback(NULL)
+:	mFocusLostCallback(nullptr),
+	mFocusReceivedCallback(nullptr),
+	mFocusChangedCallback(nullptr),
+	mTopLostCallback(nullptr)
 {
 }
 
@@ -146,14 +146,14 @@ struct LLFocusMgr::Impl
 LLFocusMgr gFocusMgr;
 
 LLFocusMgr::LLFocusMgr()
-:	mLockedView( NULL ),
-	mMouseCaptor( NULL ),
-	mKeyboardFocus( NULL ),
-	mLastKeyboardFocus( NULL ),
-	mDefaultKeyboardFocus( NULL ),
-	mLastDefaultKeyboardFocus( NULL ),
+:	mLockedView(nullptr ),
+	mMouseCaptor(nullptr ),
+	mKeyboardFocus(nullptr ),
+	mLastKeyboardFocus(nullptr ),
+	mDefaultKeyboardFocus(nullptr ),
+	mLastDefaultKeyboardFocus(nullptr ),
 	mKeystrokesOnly(FALSE),
-	mTopCtrl( NULL ),
+	mTopCtrl(nullptr ),
 	mAppHasFocus(TRUE),   // Macs don't seem to notify us that we've gotten focus, so default to true
 	mImpl(new LLFocusMgr::Impl)
 {
@@ -163,22 +163,22 @@ LLFocusMgr::~LLFocusMgr()
 {
 	mImpl->mFocusHistory.clear();
 	delete mImpl;
-	mImpl = NULL;
+	mImpl = nullptr;
 }
 
 void LLFocusMgr::releaseFocusIfNeeded( const LLView* view )
 {
 	if( childHasMouseCapture( view ) )
 	{
-		setMouseCapture( NULL );
+		setMouseCapture(nullptr );
 	}
 
 	if( childHasKeyboardFocus( view ))
 	{
 		if (view == mLockedView)
 		{
-			mLockedView = NULL;
-			setKeyboardFocus( NULL );
+			mLockedView = nullptr;
+			setKeyboardFocus(nullptr );
 		}
 		else
 		{
@@ -188,7 +188,7 @@ void LLFocusMgr::releaseFocusIfNeeded( const LLView* view )
 
 	if( childIsTopCtrl( view ) )
 	{
-		setTopCtrl( NULL );
+		setTopCtrl(nullptr);
 	}
 }
 
@@ -197,7 +197,7 @@ void LLFocusMgr::restoreDefaultKeyboardFocus(LLFocusableElement* current_default
 	if (current_default_focus && mDefaultKeyboardFocus == current_default_focus)
 	{
 		setDefaultKeyboardFocus(mLastDefaultKeyboardFocus);
-		mLastDefaultKeyboardFocus = NULL;
+		mLastDefaultKeyboardFocus = nullptr;
 	}
 }
 
@@ -206,7 +206,7 @@ void LLFocusMgr::restoreKeyboardFocus(LLFocusableElement* current_focus)
 	if (current_focus && mKeyboardFocus == current_focus)
 	{
 		setKeyboardFocus(mLastKeyboardFocus);
-		mLastKeyboardFocus = NULL;
+		mLastKeyboardFocus = nullptr;
 	}
 }
 
@@ -219,7 +219,7 @@ void LLFocusMgr::setKeyboardFocus(LLFocusableElement* new_focus, BOOL lock, BOOL
 	focus_dirty = false;
 
 	if (mLockedView && 
-		(new_focus == NULL || 
+		(new_focus == nullptr ||
 			(new_focus != mLockedView 
 			&& dynamic_cast<LLView*>(new_focus)
 			&& !dynamic_cast<LLView*>(new_focus)->hasAncestor(mLockedView))))
@@ -291,7 +291,7 @@ void LLFocusMgr::setKeyboardFocus(LLFocusableElement* new_focus, BOOL lock, BOOL
 
 		// If we've got a default keyboard focus, and the caller is
 		// releasing keyboard focus, move to the default.
-		if (mDefaultKeyboardFocus != NULL && mKeyboardFocus == NULL)
+		if (mDefaultKeyboardFocus != nullptr && mKeyboardFocus == nullptr)
 		{
 			mDefaultKeyboardFocus->setFocus(TRUE);
 		}
@@ -343,7 +343,7 @@ BOOL LLFocusMgr::childHasKeyboardFocus(const LLView* parent ) const
 // Returns TRUE is parent or any descedent of parent is the mouse captor.
 BOOL LLFocusMgr::childHasMouseCapture( const LLView* parent ) const
 {
-	if( mMouseCaptor && dynamic_cast<LLView*>(mMouseCaptor) != NULL )
+	if( mMouseCaptor && dynamic_cast<LLView*>(mMouseCaptor) != nullptr )
 	{
 		LLView* captor_view = (LLView*)mMouseCaptor;
 		while( captor_view )
@@ -364,23 +364,24 @@ void LLFocusMgr::removeKeyboardFocusWithoutCallback( const LLFocusableElement* f
 	// in order to unlock it
 	if (focus == mLockedView)
 	{
-		mLockedView = NULL;
+		mLockedView = nullptr;
 	}
+
 	if (mKeyboardFocus == focus)
 	{
-		mKeyboardFocus = NULL;
+		mKeyboardFocus = nullptr;
 	}
 	if (mLastKeyboardFocus == focus)
 	{
-		mLastKeyboardFocus = NULL;
+		mLastKeyboardFocus = nullptr;
 	}
 	if (mDefaultKeyboardFocus == focus)
 	{
-		mDefaultKeyboardFocus = NULL;
+		mDefaultKeyboardFocus = nullptr;
 	}
 	if (mLastDefaultKeyboardFocus == focus)
 	{
-		mLastDefaultKeyboardFocus = NULL;
+		mLastDefaultKeyboardFocus = nullptr;
 	}
 }
 
@@ -430,7 +431,7 @@ void LLFocusMgr::removeMouseCaptureWithoutCallback( const LLMouseHandler* captor
 {
 	if( mMouseCaptor == captor )
 	{
-		mMouseCaptor = NULL;
+		mMouseCaptor = nullptr;
 	}
 }
 
@@ -470,7 +471,7 @@ void LLFocusMgr::removeTopCtrlWithoutCallback( const LLUICtrl* top_view )
 {
 	if( mTopCtrl == top_view )
 	{
-		mTopCtrl = NULL;
+		mTopCtrl = nullptr;
 	}
 }
 
@@ -481,7 +482,7 @@ void LLFocusMgr::lockFocus()
 
 void LLFocusMgr::unlockFocus()
 {
-	mLockedView = NULL; 
+	mLockedView = nullptr;
 }
 
 F32 LLFocusMgr::getFocusFlashAmt() const
@@ -516,7 +517,7 @@ void LLFocusMgr::setAppHasFocus(BOOL focus)
 	// release focus from "top ctrl"s, which generally hides them
 	if (!focus && mTopCtrl)
 	{
-		setTopCtrl(NULL);
+		setTopCtrl(nullptr);
 	}
 	mAppHasFocus = focus; 
 }
@@ -532,7 +533,7 @@ LLUICtrl* LLFocusMgr::getLastFocusForGroup(LLView* subtree_root) const
 			return static_cast<LLUICtrl*>(found_it->second.get());
 		}
 	}
-	return NULL;
+	return nullptr;
 }
 
 void LLFocusMgr::clearLastFocusForGroup(LLView* subtree_root)