Use c++17 in clang-format

src/.clang-format

@@ -34,14 +34,6 @@ IndentWidth:     4
 KeepEmptyLinesAtTheStartOfBlocks: false
 MaxEmptyLinesToKeep: 2
 NamespaceIndentation: None
-ObjCSpaceAfterProperty: false
-ObjCSpaceBeforeProtocolList: false
-PenaltyBreakBeforeFirstCallParameter: 1
-PenaltyBreakComment: 300
-PenaltyBreakFirstLessLess: 120
-PenaltyBreakString: 1000
-PenaltyExcessCharacter: 1000000
-PenaltyReturnTypeOnItsOwnLine: 200
 PointerAlignment: Left
 SpaceBeforeAssignmentOperators: true
 SpaceBeforeParens: ControlStatements
@@ -51,6 +43,5 @@ SpacesInAngles:  false
 SpacesInContainerLiterals: true
 SpacesInCStyleCastParentheses: false
 SpacesInParentheses: false
-Standard:        Cpp11
-TabWidth:        8
+Standard:        c++17
 UseTab:          Never