add better support of editor selection

[anb0s]

In the versions before pre-release v2.3.0-beta.2 the selection in editor was used to create new resource selection that just tried to find files and/or folders from selected text. The text was devided implicitly by line-endings and therefore it was sometimes not the wanted output.

With the new pre-release v2.3.0-beta.2 the text selections are not handled anymore as new resource selection but the text selection is stored in the resource object derived from the editor document resource (IResource or IFile). This was needed to implement #212 and #219 properly.

We need a special handling and options to have the resource selections configurable and explicit to avoid edge cases.

May be related to #166 and other issues that needs selection preprocessing or user dialog for explicit knowledge and decision from user.