Extract out perl package App::Cilly::CilCompiler from cilly driver into ...

...a standalone perl module reusable from other CIL apps.  (Given the package naming, it actually might have been the original intention.)

This helps other CIL apps reuse this perl module for their own perl driver scripts.  E.g.

https://github.com/pmundkur/ccured-hack/commit/368e0361f409d3d57de951d46c1b047d7cb65f47