marked getNotParenthesizedExpression method @Nullable; changed it's usages appropriately;
bit syntax parsing fix #305
added Erlang SDK R16B01 to ErlangSdkRelease enum; this fixes duplicate items when completing BIFs on R16B01;
Merge pull request #309 from deadok22/duplicated-suggestions

#293 duplicate bif completion fix
Merge pull request #307 from deadok22/parentheses-fix

fixed nullity in getNotParenthesizedExpression
cleanup