Add 3 new classes to the plugin

* Add a cache class
* Add a docset class to encapsulate docset info
* Add a profile class to encapsulate profile info

* Add dependency on funcoo.vim
Add keywords cache
Handle special cases for docset keywords
Sort docsets by name in the cache
Complete using the new cache
Show settings using the new cache
Removes obsolete code
Add dummy functions for entry points
Add function to add keywords to the current buffer
Reorganize the search function
Fix minor issues on rewrite
Adapt command and mapping names
Update the docs
Show keyword for profiles in DashSettings
Lower case all keywords
Update the Readme
Check for funcoo.vim on startup
Changes to the Readme
Update headers