Changes from Pakrat v0.8 to v0.9

Added better handling of model files in list and file chooser
Added viewing of vtf file bitmaps
Added viewing hexdump or textdump of unknown file types
Current directories for add & load operations now persistantly remembered
Added drag-and-drop of files/directories into list
Added ability to add whole directories at once
***Added auto-scan of all files referenced in map geometry & entites