docs: Sphinxify docs/tutorial/

Sorry for the massive commit, but I just wanted to knock this one down
and it is really straightforward.

There are still a couple trivial (i.e. not related to the content)
things left to fix:

- Use of raw HTML links where :doc:`...` and :ref:`...` could be used
  instead. If you are a newbie and want to help fix this it would make
  for some good bite-sized patches; more experienced developers should
  be focusing on adding new content (to this tutorial or elsewhere, but
  please _do not_ waste your time on formatting when there is such dire
  need for documentation (see docs/SphinxQuickstartTemplate.rst to get
  started writing)).

- Highlighting of the kaleidoscope code blocks (currently left as bare
  `::`).  I will be working on writing a custom Pygments highlighter for
  this, mostly as training for maintaining the `llvm` code-block's lexer
  in-tree. I want to do this because I am extremely unhappy with how it
  just "gives up" on the slightest deviation from the expected syntax
  and leaves the whole code-block un-highlighted.

  More generally I am looking at writing some Sphinx extensions and
  keeping them in-tree as well, to support common use cases that
  currently have no good solution (like "monospace text inside a link").

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@169343 91177308-0d34-0410-b5e6-96231b3b80d8

Author: chisophugis

docs/Makefile.sphinx

@@ -50,8 +50,6 @@ html:
 	@# Kind of a hack, but HTML-formatted docs are on the way out anyway.
 	@echo "Copying legacy HTML-formatted docs into $(BUILDDIR)/html"
 	@cp -a *.html $(BUILDDIR)/html
-	@mkdir -p $(BUILDDIR)/html/tutorial
-	@cp tutorial/*.html tutorial/*.png $(BUILDDIR)/html/tutorial
 	@echo "Build finished. The HTML pages are in $(BUILDDIR)/html."
 
 dirhtml: