For tables of a composite index type with the first type being a
record, membership checks with an inline index key could be
misinterpreted as a record constructor instead of an expression list.
E.g, if the table type is "global t = table[conn_id, bool] of count",
then checking membership like "[c$id, is_orig] in t" now works.
Addresses #80.
Added tests of all built-in Bro data types (including different
representations of constant values, and max./min. values), keywords, and
operators (including special properties of certain operators, such as
short-circuit evaluation and associativity).
