SI-8695  SeqLike has unintuitive implementation of combinations

Clarified what `combinations` means in the docs.
Update ScalaDoc code examples not to use deprecated constructs

- Replace newTermName in favour of TermName
- Replace newTypeName in favour of TypeName
add 0X... for hex number literal
add 0X...hex number literal in syntax summary
SI:7988 - scala.collection.JavaConverters spelling mistake

Fixed typo and cleaned up the grammar in the paragraph
SI-8995: Fix broken link in error message

Change broken link to scala-xml documentation by pointing instead to
scala-xml project.
Remove commented-out debugging code in PriorityQueue
Remove completely commented-out test/run file
Merge pull request #4172 from advancedxy/spec-fix

add 0X... for hex number literal
Merge pull request #4143 from Ichoran/issue/8695

SI-8695  SeqLike has unintuitive implementation of combinations
Merge pull request #4173 from kanielc/SI-7988

SI-7988 - scala.collection.JavaConverters spelling mistake
Merge pull request #4179 from gdickinson/remove_commented_priorityqueue_code

Remove commented priorityqueue code
Merge pull request #4166 from lpiepiora/update-scaladoc-examples

Update ScalaDoc code examples not to use deprecated constructs
Merge pull request #4174 from kanielc/SI-8995

SI-8995: Fix broken link in error message