Source code loading

[hazer-hazer]

For now, Jacy just scans the whole directory where the root file (specified in the CLI) is located.
Of course, it must be fixed, and I see to ways to do it:

1. Simple, but incorrect -- actually scan the whole directory for .jc files and throw away unused files at the name resolution stage
2. Right, but complex -- run compilation of some file just after the module tree building stage

The second variant sounds right, anyway, it comes with some problems:

• It complicates stages before the name resolution
• It would be hard to avoid bugs in it, and as far as there's the lack of testing in Jacy, I should say I will be kind of temporarily supported