Basic unit testing facilities (suites, fixtures, cases)

Added: PNimrodNode.lineinfo for better error messages from macros
Added: seq.splice

For easier use from templates and macros, except stament now supports
the list of exception types to be supplied in nkBraket node (array literal).

tests/accept/run/tunit.nim

@@ -0,0 +1,47 @@
+import
+  unittest, macros
+
+var
+    a = 1
+    b = 22
+    c = 1
+    d = 3
+
+suite "my suite":
+  setup:
+    echo "suite setup"
+    var testVar = "from setup"
+    
+  teardown:
+    echo "suite teardown"
+
+  test "first suite test":
+    testVar = "modified"
+    echo "test var: " & testVar
+    check a > b
+
+  test "second suite test":
+    echo "test var: " & testVar
+
+proc foo: bool =
+  echo "running foo"
+  return true
+
+proc err =
+  raise newException(EArithmetic, "some exception")
+
+test "final test":
+  echo "inside suite-less test"
+
+  check:
+    a == c
+    foo()
+    d > 10
+
+test "arithmetic failure":
+  expect(EArithmetic):
+    err()
+
+  expect(EArithmetic, ESystem):
+    discard foo()
+