Add: Grayed out picture for better visualization of the process

Add: Question box (Yes|No) on automatic button if the picture contains more than 10000 pixels.

Change: Now the table will be built row by row for each step forward (not always creating a whole new table)
Change: Now the rows in the table are selected if highlighted (allows keyboard input instead of always clicking)

Fix: Automatic button works now correctly and end properly

TODO:
1. Load the same picture twice in the same session will corrupt the lzw-table
2. hide rows that aren't used for highlighting
3. the last pixels aren't highlighted - don't get written into the getHighlightingArray?