Overhauled annotator almost completely

Fixed stuff:

• Elements to annotate are no longer held in elementsToAnnotate because the errors showed up after they were fixed. This should prevent a possible memory leak in case the elements were deleted or modified.
• Also, ids are not searched for in the entire file, but are rather kept track of in a map (each project has its own map to hopefully ease opening multiple projects at once). This should stop stack overflows from happening.
• Code completion, seeing Javadocs, and resolving references are possible for items in sequences.
• Arguments to mappings with the tag !!map aren't highlighted with "No such parameter" now.

Known / potential bugs:

• Deleting the entire file and undoing it may require the plugin to be restarted (the inspections tooltip should work).
• Random crashes (this shouldn't happen anymore, but I haven't tested it enough).
• The summoning of Cthulhu without warning.