Added support for configuration files

Configuration files use the same format as the --config string (except that commas can
be replaced by newlines), and can be placed in ~/.ocp/ocp-indent.conf, or in a .ocp-indent
file in any parent directory. This provides a convenient way to have per-project setups
that can be easily shared by any contributor.

Setting the ocp-indent-config variable in emacs-customise is now deprecated.
Documenting the configuration file
Fixed doc error
Clarification of a point in the doc
Setting comma for back-alignment, and some tweaking
Not applying back-alignment when token is alone on its line
small fixes

lwt_try / finally and indent of a first match case without bar when i_with>=2
Version 1.1.0
Add option 'declarative_if'. Prevents indentation of else branch.