Add basic support for renaming refactoring

[DavyLandman]

Related to https://github.com/usethesource/rascal-language-servers/pull/48 but now using the new TextEdit feature of rascal standard library.

Some questions:

• Are there any guarantees about the location of the name to be renamed (e.g. is it positioned on the complete name or not?)
• The only full proof way to do this is: fetch (or recompute) all TModels of all modules in the current project and in the given other projects. This will be very expensive!