Document from gtalk content

[jwu]

There are valuable contents in our chat. Can become document for public. I list some of the things I remember and missed in current document:

• Usage of g:exvim_custom_path, how can we use it in non-standard install of Vim.
• How to introduce a new plugin to exVim organization. (Especially those unmaintains in vim-scripts, but we want to pick it up and modified by our own purpose.)
• About folder_filter_root_only
• When should I increase .exvim version number? (This should put in document - developer manual section)
• usage of plugin_xxx#register_hotkey
• and more...