By making the caller use the "namespace" keyword, the formatter
is given the right indentation hints.
Also makes it clearer synatactically. One day, this will be a
namespace alias (needs GCC 7).
This adds a few tests on:
* LIB_PART
* SCH_PIN
* SCH_SHEET
* SCH_SHEET_PATH
These tests exercise some of the basic code paths in these classes
and show some of the expected behaviours.
None of these tests are particularly ground-breaking, but they
provide a starting point to build out further tests, and to ensure
the already-covered behaviour is stable.
It does expose some places where SCH_SHEET could probably use const.