Swift 5 version

Updated to swift 5

Update threshold and itemCount dynamically

• Dynamically update threshold and itemCount to avoid crashes

Built in scroll to top and bottom

• Builtin scroll to top and bottom function with cmd + up/down

Fixed MoveUp function

Move up function is now fixed the right way.

Bug fix

• Fixed the bug of jumping highlights when scrolled up more than once continuously
• Moved the call of keyPressed() before the actual highlight move

Initial release

• Fully documented
• Fixed permission issues
• Supports Carthage