Added matchers:
addrLabelExpr
atomicExpr
binaryConditionalOperator
designatedInitExpr
designatorCountIs
hasSyntacticForm
implicitValueInitExpr
labelDecl
opaqueValueExpr
parenListExpr
predefinedExpr
requiresZeroInitialization
stmtExpr
Enable ConditionOperator-related matchers for BinaryConditionalOperator also
Enable hasSourceExpression() for OpaqueValueExpr
Can we put gnu in the name of matchers that only match GNU extensions?