[LanguageSpecificURIEditorOpener] Make editorID configurable independent from language name see https://bugs.eclipse.org/bugs/show_bug.cgi?id=456068
[xtext][ui] Case sensitive outline filtering was enabled too eager

see https://bugs.eclipse.org/bugs/show_bug.cgi?id=393439

Change-Id: Ia8ab86fc58cde363e75294133e390921f2a5ac05
Merge "[LanguageSpecificURIEditorOpener] Make editorID configurable independent from language name see https://bugs.eclipse.org/bugs/show_bug.cgi?id=456068"