merge reveal templates into one

there was very fine-grained subclassing in reveal_internals,
which I don't think was beneficial.
update components

to latest in ipython-components

closes #4765
we don't bundle lessc anymore, remove its vestiges
marked now adds ids to header tags
reorder slide branch per review
Correct order of packages for unicode
Merge pull request #4806 from richardeverson/ucs

Correct order of packages for unicode in nbconvert to LaTeX
Merge pull request #4796 from minrk/update-components

update components

closes #4765
Merge pull request #4795 from minrk/single-reveal-template

merge reveal templates
a minor typo in the code mirror stuff
document tab and shift-tab in codemirror
fix Sphinx table rendering, thanks @Carreau
Merge pull request #4811 from ivanov/cm-typos

document code mirror tab and shift-tab
update CodeMirror to 3.21

and require.js to 2.1.10

closes #4812
fix regex for cleaning old logs with ipcluster

it still had the 'z' suffix from ages and ages ago, so no files would ever match.

closes #4810
Fix typos in parallel doc
Fix inconsistencies in parallel direct interface doc

Running through the entire page would produce errors, as different
variable names were used, or, in the case of the %px a=b example, not
throw an exception because a and b actually were defined in an earlier
example.

The following fixes allow one to follow through the entire page and
experience the expected behaviors
Merge pull request #4823 from adamatus/parallel-doc-fixes

Minor fixes for typos/inconsistencies in parallel docs
Merge pull request #4819 from minrk/cm3.21

update CodeMirror to 3.21
Error in Session.send_raw()

Addresses issue ipython/ipython/#4839.