math incorrect error on logical operations

[mqudsi]

We've previously decided that the new math will not support boolean/logical operations (#4777), but it currently emits an error that isn't very helpful or strictly accurate:

mqudsi@Blitzkrieg /m/c/U/Mahmoud> math "42 > 1337"
math: Error: Missing operator
'42 > 1337'
    ^

especially because that helpful caret is, in fact, pointing pointing to an operator.. just not one that is supported.

We should probably catch some common boolean/logical operations and print a more helpful message telling the user to use test instead.