Implement BooleanValue type, and add default and binary evaluation for boolean type

[daeisbae]

Changes

• Implement BooleanValule type #48
• Add boolean type in default evaluation function #48
• Add boolean in binary evaluation funciton #48

Demo

./AParser                                                                                                                               ─╯
>>> true
true
>>> false
false
>>> set hello = true
true
>>> hello + 35
36
>>> true - false
1
>>> true + true
2
>>> true * true
1
>>> true / true
1