Implement all of PHP's operators

[ryangjchandler]

https://www.php.net/manual/en/language.operators.precedence.php provides a list of operators ordered by their precedence. We support quite a few of these already but there's some things like bitwise ops and casts that still need to be implemented.

Unary

• All casts ((int), (bool), etc.)
• Plus (+)
• Bitwise not (~)
• Prefix decrement (--$i)
• Prefix increment (++$i)
• Error control (@)
• Print (print)

Binary

• Modulo (%)
• Left shift (<<)
• Right shift (>>)
• Bitwise and (&)
• Bitwise or (|)
• Bitwise xor (^)
• Not equal (<>)
• Spaceship (<=>)
• Logical and (and)
• Logical or (or)
• Logical xor (xor)

Assignment

• Assign =
• Add assign +=
• Sub assign -=
• Mul assign *=
• Pow assign **=
• Div assign /=
• Concat assign .=
• Mod assign %=
• Bitwise and assign &=
• Bitwise or assign |=
• Bitwise xor assign ^=
• Left shift assign <<=
• Right shift assign >>=
• Null coalesce assign ??=

[edsrzf]

Here's a list of operators I've found that still need to be implemented:

See description.

[ryangjchandler]

Before implementing some of these, the precedence system needs some improvements I think. I'm not a huge fan of the binding power system I've got in place right now and would ideally like to move to a Precedence enum and then an Associativity enum too.. I think.

[ryangjchandler]

@edsrzf Moved your list into the issue description.