Fix candidate evaluation for multi-file projects (#402)

[Gal-bloch]

Summary

This PR fixes an issue where OpenEvolve was not properly evaluating programs that depend on multiple files (e.g., Java projects with multiple .java files).

Problem

When using OpenEvolve with non-Python programs that have dependencies on other files in the same directory, the evaluator was only writing the modified program code to a temporary file without copying the supporting files. This caused evaluations to always use the initial program content instead of the evolved code.

Solution

Modified the Evaluator class to:

• Accept an initial_program_path parameter
• For non-Python programs, create a temporary directory that includes all files from the source directory
• Replace the evolving file with the modified program code
• This ensures all dependent files are available during evaluation

Changes

• Added initial_program_path parameter to Evaluator.__init__()
• Modified evaluate_program() to copy source directory for non-Python files
• Updated Controller to pass the initial program path to the evaluator

Testing

The fix ensures that multi-file projects (like Java with TestFile.java + CodeFile.java) work correctly by providing all necessary files to the evaluation environment.

Fixes #402

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