Support export jar with sources

[jdneo]

From user's feedback

I would like to see support to export source files into jar files when exporting to jar

[jdneo]

@CsCherrYY Is this supported in other IDEs?

[CsCherrYY]

in eclipse, it's "export java source files and resources" option

[CsCherrYY]

in IDEA, it seems we can add module sources via

[jdneo]

Thanks for sharing. We can consider to add include source option.