Update ocp files for dependencies
Automatically update ~/.ocamlinit on init.

This should fix #185
Update CHANGES
Stop yelling when OPAM is not up-to-date. Now OPAM is (almost) stable, this is no so important.
Update CHANGES
Define the shell 'opam-switch-eval' function to switch and eval
Fix auto-completion scripts
Get ride of `eval` in some cases and start configuring OPAM globally.

This is still quite experimental, I need some feedback on that.

This is linked to #306 and #482