Add custom shortcuts

[sid-am-ahd935]

Currently, there are no shortcuts like [CTRL+R/CMD+R], etc and everything is done using the widgets only.

Solution: Add event handlers which wake up on certain shortcuts and trigger the necessary functions. Some examples are given below:

• CTRL + S : Shuffle
• CTRL + R : Random Generate (Regenerates blocks with random block quantity values)
• CTRL + G : Shift Focus to Input Box (where block quantity is given) -> upon enter generates the blocks with that quantity
• CTRL + 1 : Sorts the blocks using the first sorting algorithm.
• CTRL + 2 : Sorts the blocks using the second sorting algorithm.
• ...
• CTRL + W : Exit.