First working version of IQM animations

Still a work in progress but it already works...
Current riqm API could be simplified...

src/raylib.h

@@ -461,6 +461,7 @@ typedef struct Mesh {
     int vertexCount;        // Number of vertices stored in arrays
     int triangleCount;      // Number of triangles stored (indexed or not)
 
+    // Default vertex data
     float *vertices;        // Vertex position (XYZ - 3 components per vertex) (shader-location = 0)
     float *texcoords;       // Vertex texture coordinates (UV - 2 components per vertex) (shader-location = 1)
     float *texcoords2;      // Vertex second texture coordinates (useful for lightmaps) (shader-location = 5)
@@ -468,9 +469,16 @@ typedef struct Mesh {
     float *tangents;        // Vertex tangents (XYZW - 4 components per vertex) (shader-location = 4)
     unsigned char *colors;  // Vertex colors (RGBA - 4 components per vertex) (shader-location = 3)
     unsigned short *indices;// Vertex indices (in case vertex data comes indexed)
+    
+    // Animation vertex data
+    float *baseVertices;    // Vertex base position (required to apply bones transformations)
+    float *baseNormals;     // Vertex base normals (required to apply bones transformations)
+    float *weightBias;      // Vertex weight bias
+    int *weightId;          // Vertex weight id
 
+    // OpenGL identifiers
     unsigned int vaoId;     // OpenGL Vertex Array Object id
-    unsigned int vboId[7];  // OpenGL Vertex Buffer Objects id (7 types of vertex data)
+    unsigned int vboId[7];  // OpenGL Vertex Buffer Objects id (default vertex data)
 } Mesh;
 
 // Shader type (generic)