Setup the new flycheck-ocaml syntax checker
Update default opam commands to newest syntax

Newer versions of opam don't do argument parsing of the first argument
after `opam config exec` so everything needs to be passed as separate
arguments in the shell (i.e. unquoted).
Merge pull request #754 from RadicalZephyr/ocaml-flycheck

Ocaml flycheck
[Add] Add 'autojump' plugin into eshell.
[Remove] Remove 'custom.el' from git.
Merge branch 'master' of https://github.com/bbatsov/prelude
[Add] guide-key support
[Remove] Remove 'guide-key' package. Helm already has a well defined package for it'
Change default font to 'source code'