Assertion failure instead of exit

Calling exit bogs down the whole test run in a test scenario.
Update util.d
Merge pull request #8 from sgraf812/master

Fail assertion instead of exiting on implementation missing
Math.PI made static immutable

It needed a this reference before. This caused an error compiling Compatability.d which is fixed by this commit.
Hack to make getImportData work from outside util

If the ImportData opCall is not in the .di file in full, GetImportData cannot be used from outside util as the compiler cannot find the source at compile time.
Merge pull request #9 from John-Colvin/patch-1

Math.PI made static immutable
remove unnecessary T=bool
Merge pull request #10 from John-Colvin/patch-2

Hack to make getImportData work from outside util
-Fix for issue #11: System.currentTimeMillis() should return milliseconds hnsecs instead of hnsecs.
Merge pull request #12 from jmcabo/master

Fix for issue #11 (System.currentTimeMillis() in phobos).