File system modules names ambiguity

[hazer-hazer]

There's the bug, that when you name file (read ignoring .jc extension) and directory with the same name -- name resolution crashes.
This bug is blocked by #3 , because we need to implement a warning of ambiguity of paths at the name resolution level.

Example of the directory structure which causes this ICE:

.
|-- module/
|   |-- some-inner-file.jc
|-- module.jc
|-- main.jc

Why it must be fixed after #3 ?

Now, the whole parent directory of the root file is parsed. This causes an error at the driver level (in Interface), and as far as Interface mostly should not handle any specific compilation logic except compilation workflow, it is incorrect to handle this error in it.
Also, it would produce more readable error messages when a user tries to import some module, except just have a file and directory located in his/her filesystem. -- We cannot forbid users to place independent Jacy files in the directory of the esource project.