Defines functions for each as autoload functions. I need to look into
weather it would be better to have this as a local function in a plugin.
The function for url encoding was taken from vim-unimpared:
https://github.com/tpope/vim-unimpaired
I don't need all the functionality it provides
The function for base64 encoding was taken from vim-base64:
https://github.com/christianrondeau/vim-base64
although I use it with mappings in the vim-unimpared style
[b and ]b base64 encode and decode respectively
[u url encodes characters that are normally encodede in a url
[U url encodes all characters
]u and ]U both urldecode all encodede characters
The shebang line is used to determine which should interpreter should be
used when executing the file
The mapping here adds the string `#!/usr/bin/env ` at the begining of
the line.
https://en.wikipedia.org/wiki/Shebang_(Unix)
Jonathan Hodgson