Downsampler issue

[jisung]

getRoundedSampleSize() method in Downsampler decreases the sample size which is an exact power of 2 returned from getSampleSize(). This is caused by using Integer.highestOneBit(exactSampleSize - 1) instead of Integer.highestOneBit(exactSampleSize). Here is some outputs for your understanding,

Current Impl.:
getSampleSize():1-> getRoundedSampleSize():1
getSampleSize():2-> getRoundedSampleSize():1
getSampleSize():3-> getRoundedSampleSize():2
getSampleSize():4-> getRoundedSampleSize():2
getSampleSize():5-> getRoundedSampleSize():4
getSampleSize():6-> getRoundedSampleSize():4
getSampleSize():7-> getRoundedSampleSize():4
getSampleSize():8-> getRoundedSampleSize():4
getSampleSize():9-> getRoundedSampleSize():8

Expected results:
getSampleSize():1-> getRoundedSampleSize():1
getSampleSize():2-> getRoundedSampleSize():2
getSampleSize():3-> getRoundedSampleSize():2
getSampleSize():4-> getRoundedSampleSize():2
getSampleSize():5-> getRoundedSampleSize():4
getSampleSize():6-> getRoundedSampleSize():4
getSampleSize():7-> getRoundedSampleSize():4
getSampleSize():8-> getRoundedSampleSize():8
getSampleSize():9-> getRoundedSampleSize():8