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WIP checkBinaryExpr untested
WIP check UnaryExpr and BasicLit untested
WIP const evalutation code.
WIP Mixed type/untyped const expressions.

Middle of writing tests
WIP failing floating-point % test
WIP Typed ConstNumbers. floating % test passing.
WIP Const numeric binary op tests done.
Added errors for numeric op (nil|bool|string)
Merge pull request #16 from 0xfaded/carl_check_consts

Looks like we've taken the red pill. Will look at the tests later, so stay tuned...