move exTpl to lib, re #4119

lib/exTpl/ArithExpression.php

lib/exTpl/ArrayNode.php

lib/exTpl/BinaryExpression.php

lib/exTpl/BooleanExpression.php

lib/exTpl/ConditionExpression.php

lib/exTpl/ConditionNode.php

lib/exTpl/ConstantExpression.php

lib/exTpl/Context.php

lib/exTpl/Expression.php

lib/exTpl/ExpressionNode.php

lib/exTpl/FunctionExpression.php

lib/exTpl/IndexExpression.php

lib/exTpl/IteratorNode.php

lib/exTpl/MinusExpression.php

lib/exTpl/Node.php

lib/exTpl/NotExpression.php

lib/exTpl/RawExpression.php

lib/exTpl/Scanner.php

lib/exTpl/SymbolExpression.php

lib/exTpl/Template.php