Show failures on same line as caller

[joemasilotti]

Failure messages are now shown on the line that initially used the assertion, not buried in the framework code.

This is done by setting default file and line parameters to each assertion method. The default for these options are __FILE__ and __LINE__, respectively, which come from Swift's implicitly defined constants. See the image below for an example.

More information can be found in this blog post, Custom Helpers in XCTest.