progress bar, directory links and functions updated

1. created 'showPreProgres' & 'showPostProgress' functions, removed all
old duplicate progress bar code and replaced with calls to these two
functions instead. much cleaner!
2. added directory check and clean options for 'create boot.img' option
(this was previously up to the user to clean the directory)
3. externalized yet another directory call for cleaner code
4. all '${editor}' commands are now executed as a background process
5. changed progress bar 'sleep' times from 1 to 0.5 for faster process
of functions