Start moving basic view pages to separate view libraries

First up - the contacts page
Convert basic folders page to View library
Convert saveimage page to View library
Convert thread page to View library
These are not used anymore
Convert basic search page to View library
Convert advanced search page to View library
Convert compose page to View library
IMP_Ui_Quota -> IMP_Quota_Ui
This method is only used internally in one class
Convert message page to View library
Convert mailbox page to View library
Cleanup getInitialPage() usage
Convert pgp page to View library
Convert smime page to View library
IMP::header() no longer needed
[mms] All basic view pages are now routed through the basic.php endpoint.