Implement shift key functionality

[return007]

There are two possible ways I can think of the shift key's behavior:

1. Either, pressing it once means that the key is down, then it toggles all the alphabets (caps to small case and vice-versa)

2. Or, user needs to explicitly keep pressing the shift key. We can keep this behavior for future enhancement since we would need to implement keyDown and keyUp for all the keys then 😿

Anyway, let's go via the simple way and later see if someone else can take up porting work to keyDown/keyUp.