Add option to save resources automatically prior to test execution

[dstango]

I happen to forget to save my files before running a test.

I'd propose to add an option (like in "Java / Refactoring") that reads something like

Save all modified resources automatically prior to executing tests

(Editors has an option "Autosave", but that only is triggered after a certain interval of inactivity)

[Bananeweizen]

See #209. If you use the standard JDT commands for launching tests (instead of the MoreUnit commands) then you are asked whether you want to save and whether you want that always.

[dstango]

See #209 (comment) for why I'd like this option :-).