Implemented tests for isEmpty and xor.
Implemented tests for U.eq and U.text.
Implemented tests for U.text(arrays).
Implemented test for text(collection).
Implemented test for U.set.
Implemented test for U.list.
Implemented test for U.map (0 entries).
Implemented test for U.map (1 entry).
Implemented test for U.map (2 entries).
Implemented test for U.map (3 entries).
Implemented test for U.map (4 entries).
Implemented test for U.subarray.
Implemented test for U.subarray (with exception).
Merge pull request #1 from mmihajlovska/master

Implemented tests for some U static utilities.