[#90] Make value return float if there is 0 after the decimal point, else convert to integer form

[daeisbae]

Changes

• Make value return float if there is 0 after the decimal point, else convert to integer form #90
• Change the number value from int to double, so it can be more precise in arithmetic calculation. However, display in integer form if it doesn't have decimal point

Problem

./AParser
>>> 1 - 1
0
>>> 1 / 3
0
>>> 1 / 5
0

Demo

./AParser
>>> 1 - 1
0
>>> 1 -- 1
2
>>> 1 / 3
0.333333
>>> 1 / 5
0.200000