Search While Delete: Pass searchDataSource to EditController in initialization.

Still a work in progress because of a lot of UI glitches. Fixes #675 (closed)

A screen recording of it in action:

Changes:

1. new computed variable "currentDataSet" in both MediaCategoryViewController and EditController that returns either searchDataSource.searchData or model.anyfiles
2. searchDataSource reference from MediaCategoryViewController is passed to EditController
3. isSearching bool now in LibrarySearchDataSource so that both view controllers maintain the same isSearching bool
4. searchBar alpha and userInteraction is changed on editControllerDidSelectMultipleItem and editControllerDidDeSelectMultipleItem