fix MemberExpression hook to avoid conflict with ArrayExpression. closes #101
fix MemberExpression hook to avoid conflict with ArrayExpression. closes #101

old implementation was brittle. it was simply getting any "[" that was before
and any "]" that was after the MemberExpression; the correct implementation is
to detect if MemberExpression is surrounded by "[]" (first non-empty adjacent
tokens).

leftstick/esformatter,Flet/esformatter,royriojas/esformatter,millermedeiros/esformatter,wbinnssmith/esformatter,stutrek/esformatter,TommyM/esformatter,glifchits/esformatter,sakabako/esformatter,uiureo/esformatter,mwdg/esformatter