Factor the search engine installation to ease the future install of new ones.
Add DuckDuckGo search engine in the default list.
Add binding `C-c U` for DuckDuckGo search
Merge pull request #476 from ardumont/add-duckduckgo-search-engine

Add DuckDuckGo to the search engines list
Merge branch 'master' of https://github.com/bbatsov/prelude
pdf export, org-mode update
slow down auto complete, so it doesn't slow me down