[SPARK-2924] remove default args to overloaded methods

Not supported in Scala 2.11. Split them into separate methods instead.

Author: Anand Avati <avati@redhat.com>

Closes #1704 from avati/SPARK-1812-default-args and squashes the following commits:

3e3924a [Anand Avati] SPARK-1812: Add Mima excludes for the broken ABI
901dfc7 [Anand Avati] SPARK-1812: core - Fix overloaded methods with default arguments
07f00af [Anand Avati] SPARK-1812: streaming - Fix overloaded methods with default arguments
Revert "[SPARK-2468] Netty based block server / client module"

This reverts commit 3a8b68b7353fea50245686903b308fa9eb52cb51.
SPARK-3028. sparkEventToJson should support SparkListenerExecutorMetrics...

...Update

Author: Sandy Ryza <sandy@cloudera.com>

Closes #1961 from sryza/sandy-spark-3028 and squashes the following commits:

dccdff5 [Sandy Ryza] Fix compile error
f883ded [Sandy Ryza] SPARK-3028. sparkEventToJson should support SparkListenerExecutorMetricsUpdate
[SPARK-3022] [SPARK-3041] [mllib] Call findBins once per level + unordered feature bug fix

DecisionTree improvements:
(1) TreePoint representation to avoid binning multiple times
(2) Bug fix: isSampleValid indexed bins incorrectly for unordered categorical features
(3) Timing for DecisionTree internals

Details:

(1) TreePoint representation to avoid binning multiple times

[https://issues.apache.org/jira/browse/SPARK-3022]

Added private[tree] TreePoint class for representing binned feature values.

The input RDD of LabeledPoint is converted to the TreePoint representation initially and then cached.  This avoids the previous problem of re-computing bins multiple times.

(2) Bug fix: isSampleValid indexed bins incorrectly for unordered categorical features

[https://issues.apache.org/jira/browse/SPARK-3041]

isSampleValid used to treat unordered categorical features incorrectly: It treated the bins as if indexed by featured values, rather than by subsets of values/categories.
* exhibited for unordered features (multi-class classification with categorical features of low arity)
* Fix: Index bins correctly for unordered categorical features.

(3) Timing for DecisionTree internals

Added tree/impl/TimeTracker.scala class which is private[tree] for now, for timing key parts of DT code.
Prints timing info via logDebug.

CC: mengxr manishamde chouqin  Very similar update, with one bug fix.  Many apologies for the conflicting update, but I hope that a few more optimizations I have on the way (which depend on this update) will prove valuable to you: SPARK-3042 and SPARK-3043

Author: Joseph K. Bradley <joseph.kurata.bradley@gmail.com>

Closes #1950 from jkbradley/dt-opt1 and squashes the following commits:

5f2dec2 [Joseph K. Bradley] Fixed scalastyle issue in TreePoint
6b5651e [Joseph K. Bradley] Updates based on code review.  1 major change: persisting to memory + disk, not just memory.
2d2aaaf [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into dt-opt1
430d782 [Joseph K. Bradley] Added more debug info on binning error.  Added some docs.
d036089 [Joseph K. Bradley] Print timing info to logDebug.
e66f1b1 [Joseph K. Bradley] TreePoint * Updated doc * Made some methods private
8464a6e [Joseph K. Bradley] Moved TimeTracker to tree/impl/ in its own file, and cleaned it up.  Removed debugging println calls from DecisionTree.  Made TreePoint extend Serialiable
a87e08f [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into dt-opt1
0f676e2 [Joseph K. Bradley] Optimizations + Bug fix for DecisionTree
3211f02 [Joseph K. Bradley] Optimizing DecisionTree * Added TreePoint representation to avoid calling findBin multiple times. * (not working yet, but debugging)
f61e9d2 [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into dt-timing
bcf874a [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into dt-timing
511ec85 [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into dt-timing
a95bc22 [Joseph K. Bradley] timing for DecisionTree internals
[SPARK-3046] use executor's class loader as the default serializer classloader

The serializer is not always used in an executor thread (e.g. connection manager, broadcast), in which case the classloader might not have the user jar set, leading to corruption in deserialization.

https://issues.apache.org/jira/browse/SPARK-3046

https://issues.apache.org/jira/browse/SPARK-2878

Author: Reynold Xin <rxin@apache.org>

Closes #1972 from rxin/kryoBug and squashes the following commits:

c1c7bf0 [Reynold Xin] Made change to JavaSerializer.
7204c33 [Reynold Xin] Added imports back.
d879e67 [Reynold Xin] [SPARK-3046] use executor's class loader as the default serializer class loader.
Merge branch 'master' into issues/SPARK-3063