string concatenation unit tests.

because we actually have a bug!

for substrings, and the corresponding unit tests.

the String class instead of the stack for logging, and get rid of
the old and useless BitField class.

hence allowing multiprocessor builds.

that 2-year old "temporary Win32 hack".

currently works for images (SDL and GDI+ loaders) and sound samples.

- removed 0 CR characters
 - removed 188 trailing whitespaces
 - replaced 537 tabs with spaces

Useage : "...[.... csg*]" equals "current mesh -CSG- the mesh in the braces".
Keywords :  CsgUnion<csgu>, CsgSubstract<csgs>, CsgAnd<csga>, CsgXor<csgx>
TODO : cleanup useless code.
TODO : Some bugs are still present, some face that disappear should not.
TODO : Correct epsilon useage (see geometry files).
TODO : Coplanar face are not handled -at all-.
TODO : Vertex count goes through the roof in case of a Xor.

TODO : second pass on coding-style, and some tweak & usage modification.

and add a simple unit test function.

Now takes an optional shader