Add simple pandoc script. 

Only html  and tex output works so far, but images are not found yet.
Workarounds to make Pandoc find images, remove some images.

Some ugly workarounds were necessary to make sure Pandoc
finds the images.
Also, had to remove some gif files, and hyperlinks in chapter titles, as
that breaks pdf generation (I put notes there instead)
Merge branch 'master' into pandoc-wip
Merge branch 'master' into pandoc-wip
Change https image links to http to enable standalone html generation.
Fix some minor error in, switch on MathML rendering in html.
Merge branch 'master' into pandoc-wip

Conflicts:
	02_cplusplus_basics/chapter.md
	16_memory/chapter.md
	17_threads/chapter.md
Tweak and improve pandoc script.
Merge branch 'master' into pandoc-wip
Merge branch 'master' into pandoc-wip

Conflicts:
	.gitignore
	16_memory/chapter.md
	17_threads/chapter.md
Use pngs instead of the deleted gifs. Cherry-picked from b71550eb.
Merge branch 'master' into pandoc-wip