This reverts commit 593b7cd6a1c70a97d41b1d955ea38732e17b896c.
This causes breakage on MSVC. I am not sure sure why, but
this is not that important, so just back it out.
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.
