Ways to indicate paths for .cmt files

Not everybody uses dune and/or merlin. Anzak should not complain about missing .merlin file if a corresponding .cmt file can be found in the same directory of a .ml file.

I propose the following behaviour: Anzak looks for a .cmt in the same directory of the corresponding .ml file. If it does not find, it uses additional paths (empty list by default). It the .cmt file is not found in any additional path, then an error message suggests to indicate paths either adding .merlin file or using -I options.

I can propose a PR in that direction.

Hi,

Sorry for the delay of my response, please feel free to submit any PR! Otherwise, I can have a look during holidays.