Clang jump to definition in preview window

Follow the code in
https://github.com/Rip-Rip/clang_complete/pull/350
Add cppman from https://github.com/aitjcize/cppman

A nice plugin, will try to add this into vim for cpp reference
Couple ideas below:
1. qucik map to search the definition or example
2. modify the code for local access
3. search for keyword under cursor
4. access the variable type for better searching
5. support root or boost? or even other html type of documents?