Kll weighted updates group2

[leerho]

These changes are relatively minor, but I want to get these in before characterization starts for Doubles.

Summary of changes in this PR

• KllDoublesHelper.java

  • Moved the "KllHeapDoublesSketch::weightedUpdateDoubles(..)" to "KllDoublesHelper.updateDouble(..)" next to where the original "updateDouble(..)" was. It should have been there in the first place.
  • Did some refactoring/optimization of the code in both of the static package-private update methods and the public update methods in "KllDoublesSketch" that make a lot more sense. It avoids unnecessary checking of invariants when the static methods are called internally.

• KllDoublesSketch.java

  • Update methods -- see previous comment
  • Changed the variable name in the toString(..) to "withDetail" rather than "withData", since both booleans show data.
  • Added a "updateMinMax(item) method that reduces code duplication as it is used in multiple places.

• KllHelper.java

  • Refactored the dataOutput(..) and toStringImpl(..) methods to improve visualization of how the new weighted (as well as the original) updates can be understood during compaction.

The following are all either documentation or variable name changes for consistency across all of KLL.

• KllSketch.java

  • Improved terminology of "empty/garbage space" to "free space"
  • The concomitant change to the "toString(..)" boolean name (see above)

• KllDirectDoublesSketch.java

  • Improved terminology of "empty/garbage space" to "free space"

• KllDirectFloatsSketch.java

  • Improved terminology of "empty/garbage space" to "free space"

• KllDoublesSketchSortedView.java

  • Improved terminology of "empty/garbage space" to "free space"

• KllFloatsSketchSortedView.java

  • Improved terminology of "empty/garbage space" to "free space"

• KllHeapDoublesSketch.java

  • Improved terminology of "empty/garbage space" to "free space"

• KllHeapFloatsSketch.java

  • Improved terminology of "empty/garbage space" to "free space"

• KllItemsSketch.java

  • Improved terminology of "empty/garbage space" to "free space"

• KllItemsSketchSortedView.java

  • Improved terminology of "empty/garbage space" to "free space"

• KllPreambleUtil.java

  • Improved terminology of "empty/garbage space" to "free space"