Closure immutability
formatting fixes on grammar
merged grammar fix
Update 14-classes.md
Merge branch 'pull-request/77' into PHP-5.6
Added examples for division by zero
added notice about diagnostic
Clarify how interface/abstract method signatures may differ
add phpt test
Merge branch 'pull-request/80' into PHP-5.6
Expression fixes
Merge branch 'pull-request/83' into PHP-5.6
improve compatibility description
Merge branch 'pull-request/78' into PHP-5.6
add pr #67
pr #73
Merge branch 'expressions-fixes' into PHP-5.6