Boolean short-circuiting versions of `AND` and `OR`

[a740g]

We need Boolean short-circuit evaluation versions of AND and OR.
VB, FreeBASIC and many other languages use the AndAlso and OrElse keywords.
This can be implemented in QB64 using _ANDALSO and _ORELSE keywords.

IF x = 0 _ORELSE y = 0 THEN
...
END IF

IF x = 0 _ANDALSO y = 0 THEN
...
END IF

@mkilgore also noted that AND and OR in QB64 are not logical operators. So, _ANDALSO and _ORELSE keywords can be implemented as logical Boolean short-circuit evaluation versions of AND and OR. Apparently, NOT is also not logical which can lead to surprising situations (ex. NOT 1 does not give a false value). So, we may need a logical version of NOT as well (ex. _LNOT)

See Logical and Bitwise Operators in Visual Basic for a more in-depth discussion on logical and bitwise operators.