string concatenation unit tests.

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.

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

reorganise the CIE-1931 and CIE-1964 tables.

a wavelength to saturated xyY function based on the standard observer
data.

white value in case we want to convert XYZ to L*a*b* with something
else than D65.

add XYZ to xyY conversion (which gives us a pretty accurate xy graph of
the sRGB gamut), and normalise XYZ using a D65 white point.

function for CIE L*a*b* values.