VisualItem.java
-Renamed "annotations" references to "tags" references.
-Added new field to track display time.

ImageItem.java
-Constructor sets display time field to 5 seconds.
-Created setDisplayTime() method for changing how long an image is displayed.

MovieItem.java
-Constructor sets display time field to the video file duration.

slideShow.java
-Changed curImgTime type from double to float.
-MovieItem and ImageItem duration checks now handled identically using VisualItem.getDisplayTime().
-Removed unused Minim object reference.

FileBrowser.java
-Changed QItem field and constructor permissions to private.