Fix #685 running all tests

[fdodino]

Now you can

• run all tests from a source folder or project
• it works also relaunch button
• when you run all tests for a project, test file appears so you can choose same test name in different wollok test files.
  A subtle problem: if you define same test names in different wollok test files

+ test
   + clientes
         - test.wtest, test name: "testing some objects"
   + facturas
         - test.wtest, test name: "testing some objects"        

but it is unlikely to happen (and to test)

• root object of test results view indicates whether you are running all tests from project or all tests for a certain file
• it shows conveniently failures or all tests
• this fixes Run test cases separately #685 , but I could not find how to define a contextual menu in outline view for WTest, so we could launch only one test

[coveralls]

Coverage increased (+0.04%) to 90.514% when pulling 89aed7c on fix-#685-running-all-tests into 83106ce on dev.