Upgrade to Checkstyle 7.6

New:

    add allowEmptyCatches parameter to WhitespaceAroundCheck. Author: liscju #3841
    NoWhitespaceBefore: Add support for varargs. Author: Robert Painsi #3718
    Google style: allow single character variables. Author: Andrei Selkin #3702
    NPathComplexityCheck: set of tokens should not be customizable by user. Author: kazachka #3797

Bug fixes:

    DesignForExtension: order of annotations change violation. Author: Andrei Selkin #3830
    AbbreviationAsWordInName: confusing violation message. Author: rnveach #3721
    Fix AbstractTypeAwareCheck when dealing with nested interfaces. Author: rnveach #3835
    IllegalTokenText in google_checks should not has BACKSPACE character . Author: rnveach #3701
    IndentationCheck: catch child indentation not checked. Author: rnveach #3803
    Indentation: Annotation with RParen on new line when followed by other annotations causes invalid expectation. Author: shawn.kovalchick #3733

Notes:

    Code coverage is not working for certain classes in checkstyle. Author: Andrei Selkin #3843
    ImportControl: improve xdoc documentation. Author: Jochen Van de Velde #2935
    reevaluate tokens in IllegalTokenText. Author: Vladislav Lisetskii #3729
    reevaluate 'default' and 'case' in google config for EmptyBlock. Author: rnveach #3748
    reevaluate tokens in checkstyle config for NeedBraces. Author: rnveach #3735
    Config: forbid assert token by Illegal token Check. Author: rnveach #3751
    reevaluate tokens in google config for OperatorWrapCheck. Author: rnveach #3749
    messages_ja.properties contains funny (wrongly machine-translated) messages. Author: SATO Yusuke #3831
    config: Remove redundant and incorrect rules from import control configuration. Author: Jochen Van de Velde #3736
    travis should skip execution if configs of other CIs are changed. Author: Roman Ivanov #3818
    doc: Add notes on import control config for inner classes. Author: Jochen Van de Velde
    Rename method in CheckUtil. Author: Vladislav Lisetskii #3820
    wercker ci should have most of testing launches on real code to shorten time of Travis execution. Author: Roman Ivanov #3798
    Typo in website documentation for JavadocMethod.. Author: Roman Ivanov #3800
    doc: Known API issues was added to reference #3810. Author: Roman Ivanov