Documentation: updated mathutils documentation

Added descriptions of the constructors, and improved the module-level
documentation.

source/blender/python/mathutils/mathutils.c

@@ -38,7 +38,18 @@
 #endif
 
 PyDoc_STRVAR(M_Mathutils_doc,
-"This module provides access to matrices, eulers, quaternions and vectors."
+"This module provides access to the math classes:\n"
+"\n"
+"- :class:`Color`,\n"
+"- :class:`Euler`,\n"
+"- :class:`Matrix`,\n"
+"- :class:`Quaternion`,\n"
+"- :class:`Vector`,\n"
+"\n"
+".. note::\n"
+"\n"
+"   Classes, methods and attributes that accept vectors also accept other numeric sequences,\n"
+"   such as tuples, lists."
 );
 static int mathutils_array_parse_fast(float *array,
                                       int size,