Need more tests

[nelsonxb]

The current tests are kinda useful for running a debugger on, but we need a lot more.

• Tests with threads resuming other threads;
• Tests for detecting corruption (how?);
• Tests verifying that error conditions have the correct return values;
• Test that C++ exceptions still work (with complex switching);
• Test thread safety (how?);

[nelsonxb]

Hmm... I reckon cc31512 deals with the second item.

[nelsonxb]

So... until now I've actually just been kind of assuming that green's current strategy will play nice with C++ exceptions? Guess that should probably also get tests.

[nelsonxb]

The second item should be properly addressed as of 17f90c5.

[nelsonxb]

First point should be OK as of b3fcacc.

[nelsonxb]

Third point done with fdec8e7.