make drag and drop events more advanced

[ColleagueRiley]

• add action type to drag events to check for enter, move and exit types
• add data type to drag and drop events for checking what type of data was dropped, files, URLs, strings, images, etc
• add x and y to dnd drop events
• rename drop.files to drop.value to be more generic
• data drop events handle one drop at a time instead of creating an array for you
• include data length alongside data for drop events

TODO:

• Allow for data types to be dropped

• Windows: add support for IDropTarget for more advanced drag 'n drop

• OSX : change the format type based on actual format type instead of defaulting to files

• finish and test Wayland Drag 'n Drop support

• test Windows

• test OSX

• test web

• allocate drop data for dnd on the heap to prevent size limitations

• fix state-checking dnd events