to get M_PI from the platform headers and cast it to float.

that lets us draw integer random values too.

in the scene where we can push and pop cameras.

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Tileset : added GetTileSize().

- removed 5 CR characters
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vertexbuffer : added TexCoordExt, which is the same as TexCoord but means "use vec4 for TexCoord"

- removed 3 CR characters
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- removed 43 CR characters
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Added UVs system with and UVs generation test (not very conclusive)

instead of "vec2 * float".

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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.

Now takes an optional shader

calls so that they take a number of vertices or indexes, not elements.