Clean-up .gitignore

 - Eclipse-files for yamcs-simulation were not ignored. Fixed
this for the future by not depending on project names.

 - Added intellij excludes
Include sample files in generated live dvlp env

Improve set-up process by automatically including
.sample files after stripping off extension.
Move selection to bottom of side nav
Improve tag-selecting and clean a bit

The tag-bar is no longer included in drag-selection. Also, prepared
some of the code for inclusion of items in side nav other than
DataViewers.
Design NavigatorItem for extension

More refactoring towards visualizing other items
than DataViewers in the center pane.
Make Zoom-in work without selecting a range as well
Fix packet tooltip hover off by 5 pix
Fix intermittent issue where archive could not be loaded

gui label for instance was being set on EDT, and not always readable by
other threads afterwards.
Fix issues with ui element states