Araq/Nimrod — pull request #1308 by flyx (2014-06-25 20:24:41+00:00)
Title: Logical operations for TSet

Added logical set operations to *sets.nim*:

* `union` (aka **`or`**)
* `intersection` (aka **`and`**)
* `symmetricDifference` (aka **`xor`**)
* `disjoint`

Also added versions of `incl` and `excl` that take another `TSet` as second argument. Added tests for new operations.