Merge pull request #1 from anezi/PSR-0

Update
Update Assign.php
Rename Assign.php to AssignExpression.php
Update and rename AssignBitwiseAnd.php to AssignBitwiseAndExpression.php
Update and rename AssignBitwiseOr.php to AssignBitwiseOrExpression.php
Update and rename AssignBitwiseXor.php to AssignBitwiseXorExpression.php
Update and rename AssignConcat.php to AssignConcatExpression.php
Update and rename AssignDiv.php to AssignDivExpression.php
Update and rename AssignMinus.php to AssignMinusExpression.php
Update and rename AssignMod.php to AssignModExpression.php
Update and rename AssignMul.php to AssignMulExpression.php
Update and rename AssignPlus.php to AssignPlusExpression.php
Update AssignRef.php
Rename AssignRef.php to AssignRefExpression.php
Update and rename AssignShiftLeft.php to AssignShiftLeftExpression.php
Update and rename AssignShiftRight.php to AssignShiftRightExpression.php
Update and rename BitwiseAnd.php to BitwiseAndExpression.php
Update and rename BitwiseNot.php to BitwiseNotExpression.php
Update and rename BitwiseOr.php to BitwiseOrExpression.php
Update and rename BitwiseXor.php to BitwiseXorExpression.php