Added enum describing sample type.
Sample format, unit tests.
Added namespaces to sample format test.
sample_format_c: Refactor in test.

- Factored ctor param out of ctor test into common.
sample_format-c: Refactorin test.

gtest apparently explodes if you use a test with the same name from different
namespaces in the same module.

- Removed per-suit namespaces.
sample_format_c: Comparisons, unit tests.