[AdBlockRule] Save some memory with dynamic allocation and removing member variables

m_regExpStrings are now also dynamically allocated only for RegExp rules
m_cssSelector is now merged with m_matchString (m_matchString was empty
for Css Rules)
[Crash] Fixed crash after closing first app window

Always create BrowserWindow with MainApp::createWindow (even in MainApp
constructor).
Regression from recent commits.
[CloseOnLastTab] Changed behavior of "Don't quit upon closing last tab" option

It is now "Don't close window upon closing last tab", as it is more
reasonable to bind it to window, not the whole app.

Instead of loading the url-on-new-tab, it now simply blocks closing last
tab
[CloseOnLastTab] Instead of blocking closing tab, load new-tab-url
[ComboTabBar] When removing tabs, don't use timer for enabling updates

Also fixed Show Site Info action in SiteInfoWidget
[CodeCleanup] Removed all disconnectObjects() methods

I don't think we need this hack anymore.