Menu button for searching messages

Changes:

5d1ee82ea2213e188c8a8e0d720bd7f97edac23b:  Add a menu button for searching messages.  Recent phones frequently do not have a hardware search key, so there is no way to initiate a search without a menu option.  This is related to issues 3386, 3428, 4523, and 4643.  This also opens up the ability to search remote IMAP folders on those phones.

c0dd96a26904880f2b6f273edb79df5c0359f9e8:  Add a search button for finding folders in the folder list (or when selecting a folder for a copy/move operation).  Granted, there already was a menu option for searching -- this just makes it easier to access and provides some consistency with the new search button on the message list.

a74abd24c8e927ff63e61b9c6bd4c0d4669901d2 and ad34ec3d0c22189dc1f6d5c76f861c615a99b442:  Limit search results to messages in the folder searched.  If a user wants to (locally) search all folders, he can do so from the accounts list.

4634696588f072c550e7c9c2dd15ee8110cac601:  Provide a progress indicator for searches. Searches can be slow, so users need an indicator.  The indicator is also used when opening a message list or when refreshing it, or when loading more messages.  If there is a "check mail" menu button visible, then it is used as the progress indicator, otherwise an indicator is put in the action bar to the right of the title.

cf36e75dea8c3775ef3db4f8e1b246b9aa8c44dd:  Remove the progress indicator from the message list footer.  More often than not, it wasn't useful because it was scrolled out of view. The new progress indicator mentioned above serves the same purpose and is always in view.

0a91d5e2229d719150316551d100860a3eac8242:  Enable "Load up to x more" for remote searches.  This gives the user the ability to continue a remote search beyond his Server Search Result Limit setting.

f275ec1d0010f54ef19859f47f812c33d684ff9f and 345a0473b3d6f76f5d25f52ee97dec367e0eaff4:  Bug fixes.