function removeTwoSpacing(v) {
  v &= 0x09249249;
  v = (v ^ (v >> 2)) & 0x030c30c3;
  v = (v ^ (v >> 4)) & 0x0300f00f;
  v = (v ^ (v >> 8)) & 0xff0000ff;
  v = (v ^ (v >> 16)) & 0x000003ff;
  return v;
}
Removes two bits of spacing between bits. This is the opposite of insertTwoSpacing.

Example:
 input: 72
 input (binary):  1001000
                   ^^ ^^ (removed)
 output (binary): 110
 output: 6

@private
@param {number} v A 30-bit unsigned integer.
@returns {number} A 10-bit unsigned integer.
@see {@link https://fgiesen.wordpress.com/2009/12/13/decoding-morton-codes/}