We already have the convenient degrees() and radians() functions to convert
between angle formats. This commit involves a lot of refactoring here and
there and I may have missed some places where conversions were needed. But
hopefully there aren’t may such places.

The containers no longer force the user to use the ptrdiff_t type for
size information. For convenience, size() now always returns an int,
and the size_s() method offers a way to handle arrays with more than
2 billion elements. Internally, we still use ptrdiff_t, though.

Since so much code had to be changed, I took the opportunity to get
rid of capitalised accessors for classes that are lowercase.

Though it still is not possible to create a new window from a thread that did not init SDL

Scene rendering logic is now better

Box objects (AABB) now have the long awaited extent() and center()
methods. Corners are now called “aa” and “bb” for convenience. The
WorldEntity class uses a box3 for its AABB instead of two vec3s.
This allows us to simplify a lot of verbose code.

Reworked Primitive logic for scene rendering
FileUpdateTester works now .....

Revamped thread communication
Fixed dynamic thread Add/Remove
Added unit-test for threads !!!!

- removed 177 CR characters
 - removed 12 trailing whitespaces
 - replaced 0 tabs with spaces
 - fixed 1 svn:eol-style properties

MeshViewer first pass