== and != no longer treat boolean and typeid values as integers

The == and != operators (EEL_OP_EQ and EEL_OP_NE) no longer treat boolean
and typeid values as integers by implicitly casting them. That is, any
real or integer value is always considered different from true, false or
any typeid value when compared using these operators.

The nil type/value was always treated specially in this manner, so this
change makes things more consistent. It also makes booleans usable as
"special" values (like nil), as an alternative to out-of-band logic.