add infix operators

[danilopedraza]

There is a lot of operators to add. I already refactored the parser's code to make it easier, so there is some work to do:

• [x] add the pending operators
  • [x] Arithmetic operators (pending: /, **, %)
  • [x] Comparators (pending: /=, <, <=, >, >=)
  • [x] Bitwise operators (&, |, ^, <<, >>)
  • [x] Logic operators (&&, ||)
• [x] Test the precedence more
• [x] Test the behavior of each operator
  • [x] Logic
  • [x] Comparators
  • [x] Bitwise
  • [x] Arithmetic

[danilopedraza]

looks done to me.