Declare previously undeclared classes

I like this for TDD, I'll often typehint an interface or class that I haven't
declared yet, without this patch I'm forced to then go and declare an empty
class to continue working.

Check for false... schoolboy error
Deal with leading namespace operator
Added test for auto declared class when using allowMockingNonExistentMethods
Merge pull request #114 from davedevelopment/define-and-extend-missing-class

Declare previously undeclared classes