RFR 8133948: Add 'edit' function to allow external editing of scripts

[Sundararajan Athijegannathan]

Please ignore this webrev. I'll update it in-place and send a review 
request later..

Thanks
-Sundar

On 8/19/2015 10:02 PM, Sundararajan Athijegannathan wrote:
> Forgot to CC Jan ...
>
> -Sundar
>
> On 8/19/2015 10:01 PM, Sundararajan Athijegannathan wrote:
>> Please review http://cr.openjdk.java.net/~sundar/8133948/ for 
>> https://bugs.openjdk.java.net/browse/JDK-8133948
>>
>> Note: ExternalEditor and EditPad classes are from kulla/jshell code - 
>> modified to suite nashorn jjs. Perhaps eventually code could be 
>> refactored and reused from jdk.interanal.le.
>>
>> Thanks,
>> -Sundar
>