Add the new test suite.

This test suite has been in use for a long time now, in place of the obsolete and unmanageable testparser.py and testfuncs.py. It verifies the complete optimizer output to stdout and stderr, to ensure that the output matches the expectations.

See unit_tests/README.txt for more info.

unit_tests/builtins-coverage-4.txt

@@ -0,0 +1,21 @@
+const key a="\t"
+event ev(integer i)
+event ev(integer i)
+quaternion x(integer i)
+void x(integer i)
+blah x1(integer i)
+integer x2(unknown i)
+blah
+const vector a = <4,5,3,2>
+const vector a = <4,5,3,2
+const vector a = <x,4,3>
+const vector a = <4,x,3>
+const vector a = <3,4,x>
+const rotation a = <3,4,4,x>
+const list l = []
+const quaternion q=<1,2,3,4>
+const string v="
+const string q="\t"
+const unknown x3 = 3
+const list L = [1]
+const list L2 = [