TrackChanges: type after CTRL+A after choosing a match

problem:

• open a task with LanguageResources
• open a segment with an empty target
• double click on a match
• in the segment's target (= now with the chosen match in INS-tags): select all content with CTRL+A
• now type "a" (or "abc")
• the "a" is not marked with INS-Tags, only the following characters

fixed:

• If everything in the editor is within an INS-node, rangy does not recognize that the INS-node is selected, too.
• SpellCheck: handleRemovePlaceholdersInEditor() lost bookmark while removing TrackChange-placeholders.
• checking if everything is selected now also works for CTRL+A