Closes #24
Enabled keyboard input for Calculator app so that user can use keyboard for enterring numbers and performing basic operations.
Here's description of keys that can be used :-
"+" for adding
"-" for subtracting
"*" for multiplying
"/" for division
"^" for exponent
"!" for factorial
"delete" and "c" for clearing the input area
"Enter" in place of '=' button
Closes #24 Enabled keyboard input for Calculator app so that user can use keyboard for enterring numbers and performing basic operations. Here's description of keys that can be used :- "+" for adding "-" for subtracting "*" for multiplying "/" for division "^" for exponent "!" for factorial "delete" and "c" for clearing the input area "Enter" in place of '=' button