(1) rules that we enforce.
(2) rules that we would like to enforce, but haven't cleaned up the codebase to
    turn on yet (or we need to make the scalastyle rule more configurable).
(3) rules that we don't want to enforce.

Author: Reynold Xin <rxin@databricks.com>

Closes #6543 from rxin/scalastyle and squashes the following commits:

beefaab [Reynold Xin] [SPARK-7986] Split scalastyle config into 3 sections.

Author: Reynold Xin <rxin@databricks.com>

Closes #6541 from rxin/trailing-whitespace-on and squashes the following commits:

f72ebe4 [Reynold Xin] [SPARK-3850] Turn style checker on for trailing whitespaces.

Author: Reynold Xin <rxin@databricks.com>

Closes #6536 from rxin/structural-type-checker and squashes the following commits:

f833151 [Reynold Xin] Fixed compilation.
633f9a1 [Reynold Xin] Fixed typo.
d1fa804 [Reynold Xin] [SPARK-7979] Enforce structural type checker.

Author: Reynold Xin <rxin@databricks.com>

This patch had conflicts when merged, resolved by
Committer: Reynold Xin <rxin@databricks.com>

Closes #6527 from rxin/covariant-equals and squashes the following commits:

e7d7784 [Reynold Xin] [SPARK-7975] Enforce CovariantEqualsChecker

Author: Reynold Xin <rxin@databricks.com>

Closes #6528 from rxin/style-finalizer and squashes the following commits:

a2211ca [Reynold Xin] [SPARK-7976] Enable NoFinalizeChecker.

This is a follow-up patch to #6441.

Author: Andrew Or <andrew@databricks.com>

Closes #6510 from andrewor14/extends-funsuite-check and squashes the following commits:

6618b46 [Andrew Or] Exempt SparkSinkSuite from the FunSuite check
99d02ac [Andrew Or] Merge branch 'master' of github.com:apache/spark into extends-funsuite-check
48874dd [Andrew Or] Guard against direct uses of FunSuite / FunSuiteLike

[SPARK-7940] Enforce whitespace checking for DO, TRY, CATCH, FINALLY, MATCH, LARROW, RARROW in style checker.

…

Author: Reynold Xin <rxin@databricks.com>

Closes #6491 from rxin/more-whitespace and squashes the following commits:

f6e63dc [Reynold Xin] [SPARK-7940] Enforce whitespace checking for DO, TRY, CATCH, FINALLY, MATCH, LARROW, RARROW in style checker.

This is the last batch of changes to complete SPARK-7929.

Previous related PRs:
https://github.com/apache/spark/pull/6480
https://github.com/apache/spark/pull/6478
https://github.com/apache/spark/pull/6477
https://github.com/apache/spark/pull/6476
https://github.com/apache/spark/pull/6475
https://github.com/apache/spark/pull/6474
https://github.com/apache/spark/pull/6473

Author: Reynold Xin <rxin@databricks.com>

Closes #6487 from rxin/whitespace-lint and squashes the following commits:

b33d43d [Reynold Xin] [SPARK-7929] Turn whitespace checker on for more token types.

This builds on my earlier pull requests and turns on the explicit type checking in scalastyle.

Author: Reynold Xin <rxin@databricks.com>

Closes #5342 from rxin/SPARK-6428 and squashes the following commits:

7b531ab [Reynold Xin] import ordering
2d9a8a5 [Reynold Xin] jl
e668b1c [Reynold Xin] override
9b9e119 [Reynold Xin] Parenthesis.
82e0cf5 [Reynold Xin] [SPARK-6428] Turn on explicit type checking for public methods.

Author: Reynold Xin <rxin@databricks.com>

Closes #5125 from rxin/core-explicit-type and squashes the following commits:

f471415 [Reynold Xin] Revert style checker changes.
81b66e4 [Reynold Xin] Code review feedback.
a7533e3 [Reynold Xin] Mima excludes.
1d795f5 [Reynold Xin] [SPARK-6428] Added explicit types for all public methods in core.

Author: prudhvi <prudhvi953@gmail.com>

Closes #2799 from prudhvije/ScalaStyle/space-after-comment-start and squashes the following commits:

fc263a1 [prudhvi] [Core] Using scalastyle to check the space after comment start

...erators.

Author: Prashant Sharma <prashant.s@imaginea.com>

Closes #2358 from ScrapCodes/scalastyle-unicode and squashes the following commits:

12a20f2 [Prashant Sharma] [SPARK-2182] Scalastyle rule blocking (non keyboard typeable) unicode operators.

Author: Prashant Sharma <prashant.s@imaginea.com>

Closes #124 from ScrapCodes/SPARK-1096/scalastyle-comment-check and squashes the following commits:

214135a [Prashant Sharma] Review feedback.
5eba88c [Prashant Sharma] Fixed style checks for ///+ comments.
e54b2f8 [Prashant Sharma] improved message, work around.
83e7144 [Prashant Sharma] removed dependency on scalastyle in plugin, since scalastyle sbt plugin already depends on the right version. Incase we update the plugin we will have to adjust our spark-style project to depend on right scalastyle version.
810a1d6 [Prashant Sharma] SPARK-1096, a space after comment style checker.
ba33193 [Prashant Sharma] scala style as a project

SPARK-1058, Fix Style Errors and Add Scala Style to Spark Build. Pt 2

Continuation of PR #557

With this all scala style errors are fixed across the code base !!

The reason for creating a separate PR was to not interrupt an already reviewed and ready to merge PR. Hope this gets reviewed soon and merged too.

Author: Prashant Sharma <prashant.s@imaginea.com>

Closes #567 and squashes the following commits:

3b1ec30 [Prashant Sharma] scala style fixes

SPARK-1058, Fix Style Errors and Add Scala Style to Spark Build.

Author: Patrick Wendell <pwendell@gmail.com>
Author: Prashant Sharma <scrapcodes@gmail.com>

== Merge branch commits ==

commit 1a8bd1c059b842cb95cc246aaea74a79fec684f4
Author: Prashant Sharma <scrapcodes@gmail.com>
Date:   Sun Feb 9 17:39:07 2014 +0530

    scala style fixes

commit f91709887a8e0b608c5c2b282db19b8a44d53a43
Author: Patrick Wendell <pwendell@gmail.com>
Date:   Fri Jan 24 11:22:53 2014 -0800

    Adding scalastyle snapshot